Water Quality

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Redwood City Water Quality Information

Flushing Program Facts
Redwood City 2025 Public Health Goal Report
Water Fluoridation in your drinking water
Taste and Odor Fact Sheet

Currently, all Redwood City’s drinking water is supplied by the San Francisco Regional Water System (SFRWS), operated by the San Francisco Public Utilities Commission (SFPUC). The SFRWS, also known as the Hetch Hetchy Water System, provides high quality drinking water to over 2 million people in the Bay Area. The SFPUC maintains a watershed control program that effectively limits or eliminates potential contamination to the water supply. The Hetch Hetchy water supply meets all federal and State criteria for watershed protection, disinfection treatment, bacteriological quality and operational standards, allowing the SFPUC and Redwood City to provide its customers exceptionally high quality drinking water.

Redwood City routinely monitors the distribution system for bacteriological quality, chlorine residual, general physical parameters and disinfection by-products. The City conducts tri-annual monitoring as required for Lead & Copper, and routinely collects 23 samples per week for bacteriological analysis from 51 dedicated sampling stations throughout the water distribution system.

Redwood City's Annual Water Quality Reports

Current Report: 2024

Past Reports:

2023
2022	2021	2020	2019
201 8	201 7	201 6	201 5
201 4	201 3	201 2	201 1
20 10	200 9	200 8	200 7
200 6	200 5

Water Service Line Inventory

As part of efforts to remove lead water pipes from water systems nationwide, the United States Environmental Protection Agency and California State Water Resources Control Board updated the Lead and Copper Rule regulations to require all water systems to create an inventory of water service line materials in their respective systems. Water service lines have a City owned portion from the water main in the street to the water meter and a private customer owned portion from the water meter to the building. Prior efforts in Redwood City determined that no City owned portion of the service lines contain lead. Beginning in 2021 and concluding in October 2025 the City inspected the material of the customer owned portion of service lines. During the inspections no lead service lines were found. A complete listing of the inventory is available below.

Water Service Line Inventory

Water Utility Service Line

How to identify the material of your service line:

Material	Color	Magnetic	Other Characteristics	Example
Plastic	- Black - White - Blue	No
Copper	- Brown - Reddish brown	No	- Shiny like a new penny - Brown like an old penny. - May have green tarnishing
Brass	- Yellow - Gold - Brown	No	- Has threads - Hard material - Has threads
Galvanized	- Dull gray - Shiny when new - May be rusty - May have rust spots	Yes	- Has threads - Hard material - Not easy to scratch
Lead	- Gray, - Shiny when scratched	No	- No threads - Easy to scratch

Water Source Blend Change Notices

The SFPUC provides notice to Redwood City and other wholesale customers of the SFRWS when the source of water must be changes to perform maintenance on the SFRWS or due to changes in water demand. If you have questions regarding a recent water blend change notice or another water quality related issue please contact Redwood City Public Works Services at (650) 780-7464, or submit a Water Quality service request through myRWC.

Water Quality FAQ

Expand/Contract Questions and Answers

After flushing my pipes, my cold water runs clear but my hot water is still discolored. What should I do?
If discolored water has been drawn into the hot water system, the hot water can continue to be used until the discoloration dissipates and is no longer an aesthetic issue.
Have your water tested for lead.
We have no known lead service lines in Redwood City, and have been replacing brass meters with lead-free meters since 2002. However, some homes in Redwood City may have increased levels of lead in their tap water caused by deterioration of household plumbing materials that contain lead. Infants and young children are typically at the greatest health risk. If you are concerned about elevated lead levels in your water, flush your tap for 30 seconds to 2 minutes before using the water whenever the tap has not been used for several hours, and have your water tested. Testing can be performed by drinking water laboratories and generally costs around $50.
How can I have my home water quality tested?
If you would like your home water tested, contact an accredited laboratory from the State Water Resources Control Board’s interactive map. You should check that the laboratory has an active accreditation status before using it. Also, a laboratory may not be certified for all constituents of interest, so you should ask if they are ELAP-certified for the analysis requested before ordering a test.

Note: The City is providing this information as a convenience to customers and is not endorsing any particular laboratory. The City makes no representations or warranties concerning the accuracy of their results, methodologies employed, or fees charged.
How much Lead is produced and released to the environment?
Lead may occur in drinking water either by contamination of the source water used by the water system, or by corrosion of lead plumbing or fixtures. Corrosion of plumbing is by far the greatest cause for concern. All water is corrosive to metal plumbing materials to some degree. Grounding of household electrical systems to plumbing may also exacerbate corrosion. Over time, lead-containing plumbing materials will usually develop a scale that minimizes further corrosion of the pipe.
How will I know if Lead is in my drinking water?
If the levels of lead exceed the Action Level, PWS must notify the public via newspapers, radio, TV and other means. Customers will be informed of what they can do at home to lower their exposure to lead. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.
How will Lead be detected in and removed from my drinking water?
Since lead contamination generally occurs from corrosion of household lead pipes, it cannot be directly detected or removed by Redwood City. Instead, EPA requires water systems to control the corrosiveness of their water if the level of lead at home taps exceeds an Action Level. The Action Level for lead has been set at 15 parts per billion (ppb) because EPA believes, given present technology and resources, this is the lowest level to which water systems can reasonably be required to control the contaminant should it occur in drinking water at their customers home taps. Redwood City last conducted sampling for lead from customer taps in 2015, and all results were below the Action Level.

These drinking water standards and the regulations for ensuring these standards are met, are called National Primary Drinking Water Regulations. All public water supplies must abide by these regulations. If contaminant levels are found to be consistently above the Action level, your water supplier must take steps to reduce the amount of lead so that it is consistently below that level. Corrosion control has been approved by EPA for controlling lead.
I'm experiencing brown or yellow tinted water coming out of my faucet, what should I do?
Brown or yellow tinted water from your tap can be caused by disturbances in the water distribution system. Examples of disturbances that can cause discolored water are: fire hydrant use, a water main break, maintenance work, etc. If you experience brown or yellow tinted water from your tap, allow the water to settle for a short time (about 1 hour) and then flush all faucets - cold water only - in your home or business for several minutes. If possible, first flush your backyard garden hose for a few minutes before flushing indoor fixtures. If the water does not clear up after the initial flushing, repeat the flushing every half hour. The discolored water should clear within 2 hours; if it does not, please contact Redwood City Public Works at (650) 780-7464.
Is discolored water safe to drink?
Discoloration often occurs when there are disturbances in the water distribution system such as main breaks, hydrant flushing, or construction. Discolored water caused by iron and manganese oxide sediment is safe to drink. During such discolored water episodes, your water continues to meet all state and federal drinking water standards for public health and safety.
Learn more about your drinking water!
The EPA strongly encourages people to learn more about their drinking water, and to support local efforts to protect and upgrade the supply of safe drinking water. Your water bill and Public Works Services are good starting points. PWS can provide you with a list of the chemicals tested for in your water, as well as a description of how your water is treated. Phone number? (650) 780-7464.

For information on drinking water in general, call EPA’s Safe Drinking Water Hotline: (800) 424-5323.
What are the health effects?
Short- and Long-term effects: Lead can cause a variety of adverse health effects when people are exposed to it at levels above the MCL for relatively short periods of time. These effects may include interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, slight deficits in the attention span, hearing, and learning abilities of children, and slight increases in the blood pressure of some adults.

Long-term effects: Lead has the potential to cause the following effects from a lifetime exposure at levels above the MCL: stroke and kidney disease; cancer.
What happens to Lead when it is released to the environment?
When released to land, lead binds to soils and does not migrate to ground water. In water, it binds to sediments. It does not accumulate in fish, but does in some shellfish, such as mussels.
What is Lead and how is it used?
Lead is a metal found in natural deposits as ores containing other elements. It is sometimes used in household plumbing materials or in water service lines used to bring water from the main to the home. See how to identify and purchase lead-free faucets.
What is Unidirectional Flushing?
Works Services Department operates a unidirectional flushing program, which is a proactive approach to preventing water quality problems and ensuring the highest quality of water.

Unidirectional flushing consists of closing appropriate water system valves and opening fire hydrants in a sequential manner to create one-way flow in the distribution system. The rate of flow and discharge at the fire hydrants is adjusted to achieve a desired velocity or flow of water in the pipes. Water flushed at the desired velocity produces a scouring action in the pipes, removing deposits, encrustations and sediments. Hydrants are flushed until a desirable water quality is achieved.
What should I do if my water becomes discolored?
1. Run the outside front hose bib at full force for a few minutes or until the water clears. Be sure to disconnect any garden hose.

2. If the water does not clear after a few minutes, wait another hour and repeat the process until the water is clear at the outside front hose faucet.

3. Flush the cold-water faucets throughout the house. Start by flushing the cold-water faucet in the bathtub. If you are concerned about wasting water, water the backyard from the backyard hose bib for several minutes or until the water clears.

4. After the tub or backyard faucet runs clear, flush all of the other cold water household faucets; starting from the front of the house (nearest the street), then the rest of the cold water faucets within the home.
5. If necessary, remove faucet aerators, clear any particles, and then reinstall them. If the water still fails to clear, contact Redwood City Water Quality at (650) 780-7462.
Why does the City flush water out of hydrants?
The Public Works Services Department routinely flushes the water pipelines to remove impurities, sediment, or other materials that may have deposited in the distribution system. These deposits, which have settled out and accumulated in pipelines, may result in taste, odor, and turbidity problems. Additionally, routine flushing of dead-end pipelines removes water with low chlorine residuals and accumulated deposits ensuring, that your water tastes great and that you receive the highest quality of water from your tap.
Why is Lead being regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of chemicals in drinking water which do or may cause health problems. These non-enforceable levels, based solely on possible health risks and exposure, are called Maximum Contaminant Level Goals (MCLG), which are set at zero because EPA believes this level of protection would not cause any potential health problems.

Redwood City Water Quality Information

Redwood City's Annual Water Quality Reports

Water Service Line Inventory

Water Source Blend Change Notices

2026

2025

2024

Water Quality FAQ

After flushing my pipes, my cold water runs clear but my hot water is still discolored. What should I do?

Have your water tested for lead.

How can I have my home water quality tested?

How much Lead is produced and released to the environment?

How will I know if Lead is in my drinking water?

How will Lead be detected in and removed from my drinking water?

I'm experiencing brown or yellow tinted water coming out of my faucet, what should I do?

Is discolored water safe to drink?

Learn more about your drinking water!

What are the health effects?

What happens to Lead when it is released to the environment?

What is Lead and how is it used?

What is Unidirectional Flushing?

What should I do if my water becomes discolored?

Why does the City flush water out of hydrants?

Why is Lead being regulated?