Question 1

Do you know where the main water shut-off is?

Accepted Answer

If you have a leak, find the main shut-off before the plumber arrives. It's usually in the basement, utility room, or near the water meter. Knowing this prevents extra damage while you wait.

Question 2

What kind of pipes do you have?

Accepted Answer

Copper, PEX, or PVC — knowing your pipe material helps the plumber bring the right fittings on the first visit.

Question 3

Is the water still on, and is the leak active?

Accepted Answer

Active leaks are emergencies — most plumbers offer 24/7 callouts but charge extra. If you can shut off water and wait, day-rate work is much cheaper.

Question 4

Have you taken photos of the leak or fixture?

Accepted Answer

A photo of the problem area + the affected fixture helps the plumber bring the right replacement parts.

Question 5

Is anyone home with a respiratory issue?

Accepted Answer

Some chemical drain treatments produce strong fumes. Mention any health concerns in advance so the pro can choose alternative methods.

Question 6

How much does a plumber cost in San Francisco?

Accepted Answer

Rates for plumbers in San Francisco, CA vary by job type. Most pros charge by the hour or per project. On HireLocal you can compare local local plumbers, see real rates and reviews, and get free quotes before you book.

Question 7

How do I find a licensed plumber in CA?

Accepted Answer

Every plumber on HireLocal is local. We check identity and, where required, licenses and insurance. Browse plumbers in San Francisco, CA to see local pros and read reviews from neighbors.

Question 8

What should I look for when hiring a plumber in San Francisco?

Accepted Answer

Look for a licensed, insured pro with recent reviews in your area. On HireLocal you can see each pro's rating, review count, and service area. Get free quotes from several plumbers in San Francisco to compare.

Question 9

What is a Licensed plumber?

Accepted Answer

A plumber who has met state or local requirements (education, apprenticeship, and exams) and holds a valid license to perform plumbing work. Licensing protects consumers by ensuring the professional knows codes and safety practices.

Question 10

What is a Journeyman plumber?

Accepted Answer

A plumber who has completed an apprenticeship (typically 4–5 years) and passed a journeyman exam. They can work independently under the general oversight of a master plumber. Requirements vary by state.

Question 11

What is a Master plumber?

Accepted Answer

A plumber who has met additional experience and exam requirements beyond the journeyman level. A master can pull permits, run a business, and supervise journeymen and apprentices. Not all states use this tier.

Question 12

What is a Tankless water heater?

Accepted Answer

A water heater that heats water on demand as it flows through the unit, rather than storing hot water in a tank. Tankless units are more energy-efficient and last longer (20+ years) but have higher upfront costs.

Question 13

What is a Sump pump?

Accepted Answer

A pump installed in a basement or crawl space pit that automatically removes accumulated water to prevent flooding. Essential in areas with high water tables or heavy rainfall. Battery backup models protect against power-outage flooding.

Question 14

What is a Septic system?

Accepted Answer

An on-site wastewater treatment system used in areas without municipal sewer. Wastewater flows into a buried tank where solids settle and bacteria break down waste; liquid drains into a leach field. Septic tanks should be pumped every 3–5 years by a licensed professional.

Question 15

What is a Slab leak?

Accepted Answer

A water leak in the copper or PEX pipes that run beneath a home's concrete slab foundation. Slab leaks are caused by corrosion, shifting soil, or poor installation. Warning signs include hot spots on the floor, the sound of running water when all fixtures are off, unexplained increases in the water bill, and cracks in the foundation. Detection typically involves acoustic listening equipment or infrared cameras. Repair methods include spot repair (jackhammering through the slab to fix the pipe), rerouting the line through the ceiling or walls, or epoxy pipe lining. Costs range from $500 for a simple spot repair to $3,000–$5,000 for rerouting.

Question 16

What is a Water hammer arrestor?

Accepted Answer

A small plumbing device installed near valves and appliances to absorb the shockwave that occurs when water flow is suddenly stopped — the loud banging noise known as water hammer. Arrestors contain a sealed air chamber and a piston that compresses when the pressure spike hits, cushioning the impact. They're installed on washing machine supply lines, dishwasher connections, and near quick-closing solenoid valves. A water hammer arrestor costs $10–$30 for the part and $100–$200 installed by a plumber. Without one, water hammer can loosen pipe joints, damage valves, and eventually cause leaks.

Question 17

What is a PEX piping?

Accepted Answer

Cross-linked polyethylene (PEX) tubing used for residential water supply lines. PEX has largely replaced copper in new construction and repiping because it's flexible (bends around corners without elbow fittings), resists corrosion and scale buildup, handles freeze-thaw cycles better than rigid pipe (it can expand without bursting), and costs 25–40% less than copper for materials and labor. PEX comes in three types: PEX-A (most flexible, best for tight bends), PEX-B (most common, good balance of cost and performance), and PEX-C (least flexible, lowest cost). It's connected using crimp rings, clamp rings, or expansion fittings. Repiping a typical home from copper to PEX costs $4,000–$8,000 versus $8,000–$15,000 for copper-to-copper.

Question 18

What is a Polybutylene pipe?

Accepted Answer

A gray plastic water supply pipe (stamped 'PB2110') widely installed in U.S. homes from 1978 to 1995 as an inexpensive alternative to copper. Polybutylene was eventually found to deteriorate from the inside out when exposed to chlorine and other oxidants in public water supplies — micro-fractures develop in the pipe walls over 10–25 years, leading to sudden, catastrophic leaks with no visible warning. An estimated 6–10 million homes in the U.S. were plumbed with polybutylene. Most plumbing professionals recommend full re-piping with PEX or copper ($4,000–$15,000 for a typical home) rather than spot repairs, because failure is progressive and unpredictable. Many insurance companies will not insure homes with polybutylene supply lines, and its presence can affect resale value. Polybutylene is easy to identify: gray (sometimes white or black) flexible tubing, typically 1/2" to 1" diameter, with copper or plastic crimp rings at connections.

Question 19

What is a Galvanized pipe?

Accepted Answer

Steel pipe coated with a layer of zinc to resist corrosion, used as the standard for residential water supply and drain lines from the 1930s through the 1960s. While the zinc coating initially protects against rust, it gradually corrodes from the inside over 40–70 years, building up mineral deposits that restrict water flow and eventually cause pinhole leaks. Homes still plumbed with galvanized pipes commonly experience low water pressure, rusty or discolored water (especially when taps are first opened), and frequent small leaks at threaded joints. A plumber can identify galvanized pipe by its gray exterior and threaded fittings — a magnet will stick to it (unlike copper). Repair options range from spot replacement of corroded sections ($200–$600) to full re-piping with copper or PEX ($3,000–$12,000), which is recommended when corrosion is widespread.

Question 20

What is a Ball valve?

Accepted Answer

A quarter-turn shut-off valve that uses a hollow, perforated, pivoting ball to control water flow. Turning the handle 90 degrees opens or closes the valve completely. Ball valves are the modern standard for main water shut-offs and branch supply lines because they are more reliable than older gate valves — they rarely seize, require no maintenance, and provide a clear visual indicator (handle parallel to the pipe = open, perpendicular = closed). Full-port ball valves have an opening the same diameter as the pipe, so they don't restrict flow. Standard ball valves cost $5–$25 at hardware stores; professional installation runs $75–$200 per valve. Every homeowner should know where their main ball valve is located and verify it turns freely at least once a year — a stuck valve during a plumbing emergency can mean thousands of dollars in water damage.

Question 21

What is a Rough-in plumbing?

Accepted Answer

Rough-in plumbing is the initial phase of a plumbing installation where all water supply lines, drain-waste-vent (DWV) pipes, and gas lines are routed through the wall cavities, floor joists, and ceiling spaces of a building before drywall, flooring, and finish materials are installed. This phase occurs after framing is complete but before insulation and drywall close up the walls. During the rough-in, a plumber installs supply pipes (typically 1/2-inch and 3/4-inch copper, PEX, or CPVC for hot and cold water), drain pipes (1-1/2-inch to 4-inch ABS or PVC), and vent pipes that extend through the roof to allow air into the drainage system and prevent siphoning of traps. Stub-outs — short pipe ends capped and protruding from walls or floors — mark the connection points for future fixtures like sinks, toilets, showers, and dishwashers. The plumber must follow precise measurements for fixture placement: toilets require a 12-inch rough-in (center of drain to finished wall), shower drains must be centered in the pan footprint, and sink drains are typically 18–20 inches above the finished floor. All rough-in work must comply with the local plumbing code (typically based on the International Plumbing Code or Uniform Plumbing Code), and a municipal inspector must approve the rough-in before walls can be closed — this is called the rough-in inspection or pressure test, where supply lines are pressurized to 40–80 PSI for a set period to check for leaks, and DWV systems are tested with air or water. Failing this inspection means tearing open any sealed walls, so getting the rough-in right is critical. Costs for rough-in plumbing in new construction range from $8,000–$15,000 for a typical single-family home, or $1,500–$4,000 per bathroom in a remodel. The rough-in typically takes 2–5 days depending on home size and complexity.

Question 22

What is a Backwater valve?

Accepted Answer

A backwater valve (also called a backflow prevention valve for sewer lines) is a one-way valve installed on a building's main sewer lateral to prevent sewage from flowing backward into the home during municipal sewer overloads, heavy storms, or main-line blockages. The valve contains a flap or gate that stays open during normal outflow but closes automatically when water pressure reverses. Many municipalities now require backwater valves in new construction and may offer rebates for retrofit installations. Professional installation typically costs $1,000–$3,000 and involves excavating the sewer line, cutting in the valve body, and restoring the landscaping. Some cities require a permit and inspection. Homeowners with finished basements should strongly consider installation — a single sewer backup can cause $10,000–$50,000+ in damage.

Question 23

What is a Toilet flange?

Accepted Answer

A toilet flange (also called a closet flange) is a pipe fitting that connects the toilet to the drainpipe in the floor and secures the toilet to the subfloor. It consists of a ring that sits flush with or slightly above the finished floor, with a pipe collar that inserts into the drain opening. The wax ring (or modern wax-free gasket) seals between the toilet base and the flange. A damaged, cracked, or corroded flange is one of the most common causes of toilet leaks at the base — water seeps out with each flush, damaging the subfloor and promoting mold. Replacing a toilet flange costs $150–$350 professionally, though the part itself is $5–$25. If the flange sits too low after new flooring is installed, a flange extender can raise it to the correct height. Common materials include PVC (most modern homes), cast iron (older homes), and stainless steel (repair flanges that bolt over damaged originals).

Question 24

What is a Shut-off valve?

Accepted Answer

A shut-off valve (also called a stop valve) allows you to cut water supply to an individual fixture, appliance, or the entire house without affecting other plumbing. Every home has a main shut-off valve where the water line enters the building — knowing its location is critical for emergencies like burst pipes. Individual fixture shut-offs are found under sinks, behind toilets, and near water heaters and washing machines. The two most common types are gate valves (round handle, twists several turns) and ball valves (lever handle, quarter-turn). Ball valves are preferred for main shut-offs because they seal more reliably and are less prone to seizing from disuse. Homeowners should test every shut-off valve annually: turn it fully off and back on to prevent mineral buildup that can freeze the valve in the open position. Replacing a stuck or leaking shut-off valve costs $100–$300 for a fixture valve and $200–$600 for a main valve, depending on accessibility and pipe material.

Question 25

What is a PVC pipe?

Accepted Answer

PVC (polyvinyl chloride) pipe is the most widely used plastic piping in residential plumbing, used primarily for drain, waste, and vent (DWV) lines. It's lightweight, inexpensive ($0.50–$2 per linear foot for common sizes), corrosion-resistant, and easy to cut and join with solvent cement. Standard white PVC (Schedule 40) handles drainage and cold-water applications; the thicker-walled Schedule 80 (dark gray) is used where higher pressure or impact resistance is needed. PVC is not approved for hot-water supply lines — it softens above 140°F (60°C) — so CPVC (chlorinated PVC, cream-colored) is used for hot water instead. Common residential PVC sizes are 1½" and 2" for fixture drains, 3" for toilet drains, and 4" for building sewers. PVC's main limitation is UV sensitivity: prolonged sun exposure makes it brittle, so exposed outdoor runs should be painted or sleeved. PVC pipe lasts 50–100 years in typical conditions. Repairs are straightforward: a plumber cuts out the damaged section and glues in new fittings, usually for $150–$350 per repair.

Question 26

What is a P-trap?

Accepted Answer

A P-trap is the curved section of drainpipe beneath every sink, tub, and shower in a home. Viewed from the side, the pipe dips down and curves back up in a shape resembling the letter P (or U when oriented differently). This curve holds a small amount of standing water — about 2–4 inches — that acts as a seal to block sewer gases from rising into the living space. Without a functioning P-trap, toxic gases like methane and hydrogen sulfide would enter through every drain. P-traps are required by plumbing codes at every fixture. They also catch small dropped items (rings, earrings) before they enter the main drain. Common materials are PVC (residential, $5–$15), ABS (black plastic), and chrome-plated brass (exposed installations under pedestal sinks, $15–$40). P-traps can clog with hair, soap scum, or food debris — a slow-draining fixture is the first sign. A plumber typically charges $100–$250 to replace a P-trap, though the part itself is inexpensive.

Question 27

What is a Vent stack (plumbing vent)?

Accepted Answer

A vent stack is a vertical pipe that extends from the drain system through the roof, allowing air into the drainage pipes so water flows freely and maintaining the water seal in P-traps. Without venting, draining water creates a vacuum that siphons water out of traps, allowing sewer gases into the home. Every plumbing fixture must be vented per code. The main vent stack (also called the soil stack) is typically 3–4 inches in diameter and exits through the roof. Individual fixtures connect to it through smaller branch vents. Common problems include clogs from bird nests, leaves, or ice in cold climates — symptoms are slow drains throughout the house, gurgling sounds, and sewer odors. A plumber can clear a blocked vent from the roof for $150–$400. Vent stack repairs or re-routing during remodels cost $300–$1,000.

Question 28

What is a Escutcheon plate?

Accepted Answer

An escutcheon plate is a decorative cover ring that hides the hole where a pipe, faucet, or valve passes through a wall, floor, or ceiling. You see them around shower valves, under kitchen sinks where supply lines enter, at hose bibs on exterior walls, and around baseboard radiator pipes. Escutcheons serve both a cosmetic purpose (covering rough-cut holes) and a functional one (blocking drafts and pests from entering through pipe penetrations). They come in chrome, brushed nickel, brass, and plastic finishes to match fixture hardware. Standard sizes are ½", ¾", and 1" to fit common pipe diameters. Prices range from $2–$15 each. Installation is simple — most split into two halves and snap around the pipe — making them a common DIY fix. However, if you notice water stains around a missing or damaged escutcheon, the issue may be a pipe leak behind the wall that requires a plumber.

Question 29

What is a Sweat fitting (soldered copper)?

Accepted Answer

A sweat fitting is the traditional method of joining copper pipes by soldering — the term "sweat" refers to the way molten solder is drawn into the gap between pipe and fitting by capillary action, appearing to "sweat" out of the joint when properly heated. The process requires four steps: cleaning the pipe end and fitting interior with emery cloth or a copper brush until they shine, applying flux paste to remove oxidation and help solder flow, fitting the pieces together, and heating with a propane or MAPP gas torch until lead-free solder (typically 95/5 tin-antimony) melts and is drawn into the joint. A properly executed sweat joint is essentially permanent and rated for the same pressure as the pipe itself. The downsides are the open flame (a fire hazard near framing and insulation, requiring a heat shield), the skill needed to avoid pinholes, and the inability to solder pipes that have any water in them. Modern alternatives like PEX with crimp fittings, push-to-connect (SharkBite), and press fittings have largely replaced sweat fittings for residential remodels, though most plumbers still consider sweated copper the gold standard for long-term durability.

Question 30

What is a Backflow prevention device?

Accepted Answer

A mechanical assembly installed on a water supply line to prevent contaminated water from flowing backward into the potable (drinking) water system. Backflow can occur when water pressure drops suddenly — from a water main break, fire hydrant use, or heavy system demand — creating a siphon effect that pulls non-potable water back into clean supply lines. The most common types are the double check valve assembly (DCVA, $200–$600 installed), the reduced pressure zone device (RPZ, $400–$1,200 installed, required for high-hazard connections like irrigation systems with chemical injectors), and the atmospheric vacuum breaker (AVB, $30–$80, used on individual hose bibs). Most municipalities require annual testing of DCVA and RPZ devices by a certified backflow tester, costing $50–$150 per test. Failure to maintain backflow devices can result in fines, water service disconnection, and in worst cases, contamination of the public water supply with pesticides, fertilizers, or sewage.

Question 31

What is a Whole-house water filtration?

Accepted Answer

A point-of-entry (POE) filtration system installed on the main water line where it enters the house, treating all water before it reaches any fixture. Unlike point-of-use (POU) filters on a single faucet, a whole-house system protects every tap, shower, washing machine, and water heater. Common technologies: sediment filter (removes particles >5 microns, $200–$600 installed), activated carbon (removes chlorine, taste, odor, some VOCs; $1,000–$3,000), catalytic carbon (removes chloramine used by many city water systems; $1,500–$4,000), and reverse-osmosis ($3,000–$8,000 for whole-house, rare due to water waste). Many homeowners stack stages: a sediment pre-filter, a carbon filter, and optionally a UV lamp for bacterial disinfection ($500–$1,500). Annual filter replacement runs $100–$400 depending on the system. Installation is a licensed plumber's job: it typically involves cutting into the main line after the shutoff valve, adding a bypass loop, and ensuring adequate water pressure downstream (most filters cause a 5–15 PSI pressure drop).

Question 32

What is a Main sewer line?

Accepted Answer

The primary underground drain pipe (typically 4-inch diameter cast iron, PVC, or clay) that carries all wastewater from a home's internal drain system to the municipal sewer or a private septic tank. The main sewer line runs from the foundation to the street or property line, usually 3–6 feet deep. Common problems include tree root intrusion (roots enter through joints and cracks), bellying (a dip in the pipe that traps waste), and pipe deterioration (especially in older cast iron or Orangeburg pipes that degrade after 50–80 years). Signs of a main sewer line problem: multiple drains backing up simultaneously, sewage smell in the yard, unusually green patches of grass over the line, and gurgling sounds from drains. Diagnosis uses a sewer camera inspection ($100–$500). Repair options range from spot repair ($1,000–$4,000) to full replacement via traditional trench ($3,000–$15,000) or trenchless pipe lining ($4,000–$20,000, which avoids destroying landscaping). Most jurisdictions require a licensed plumber for main sewer line work.

Question 33

What is a Water softener?

Accepted Answer

A point-of-entry water treatment system that removes calcium, magnesium, and other hardness minerals from household water through ion exchange — hard water flows through a resin bed that swaps calcium/magnesium ions for sodium or potassium ions. Hard water (above 7 grains per gallon / 120 mg/L) causes scale buildup inside pipes and water heaters (reducing efficiency by 15–25%), spots on dishes and glass shower doors, dry skin and hair, and increased soap/detergent usage. A properly sized water softener (30,000–60,000 grain capacity for a typical home) costs $800–$2,500 for the unit plus $200–$500 for professional installation by a licensed plumber. The system regenerates automatically every few days, using 6–12 lbs of salt per cycle. Annual maintenance costs $50–$100 for salt (40–80 lbs/month) plus an occasional resin bed replacement ($200–$400 every 10–15 years). Salt-free water conditioners ($1,500–$4,000) use template-assisted crystallization (TAC) to prevent scale without adding sodium, but don't technically soften the water.

Question 34

What is a Hot water recirculating pump?

Accepted Answer

A small pump that keeps hot water continuously or intermittently circulating through your plumbing so you get instant hot water at every faucet, eliminating the 30–120 seconds of running cold water down the drain while waiting. Two main types: dedicated-return systems (a separate return pipe from the farthest fixture back to the water heater — ideal for new construction, $500–$1,200 installed) and comfort-valve systems (use the cold-water line as the return path via a crossover valve at the farthest fixture — retrofit-friendly, $200–$500 installed). Popular models: Watts 500800 ($200, comfort-valve type), Grundfos UP15-42F ($250, dedicated-return), and Rinnai RUR series ($250–$350, integrated with tankless heaters). Timer and temperature-sensor models run only during peak-use hours, saving $30–$60/year vs. continuous circulation. A recirculating pump saves 8,000–12,000 gallons of wasted water per year for a typical family — at $0.01/gallon, that's $80–$120 in water savings alone. Professional installation takes 2–4 hours. The pump motor draws only 25–75 watts, adding $15–$40/year to electricity costs.

Question 35

What is a Backflow preventer?

Accepted Answer

A mechanical device installed on water supply lines to prevent contaminated water from flowing backward into the potable water supply. Backflow can occur when a pressure drop in the main supply (a fire hydrant opening, a water main break) creates a siphon that pulls non-potable water — from irrigation systems, hose-connected chemical sprayers, or industrial equipment — back into the drinking water system. The two most common residential types are the Reduced Pressure Zone (RPZ) assembly and the Double Check Valve Assembly (DCVA). RPZ devices ($200–$600 installed) provide the highest protection and are required for irrigation systems, pools, and fire sprinkler connections in most jurisdictions. DCVA devices ($150–$350 installed) are used for lower-risk connections like residential irrigation without chemical injection. Most municipalities require annual testing by a certified backflow tester ($50–$100 per test) to verify the internal check valves and relief valve function correctly. Failed tests typically require seal or spring kit replacement ($75–$200 in parts plus labor). Winterization is critical in freezing climates — compressed air blow-out and draining prevent the cast brass body from cracking, which is the #1 cause of backflow preventer failure in northern states.

Households	362,650
Owner-occupied share	39 %
Jobs per year (plumber)	106,542
Pros the market supports	1,372
listed on HireLocal	27
Coverage	2 %
Score	99 / 100

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