We do everything possible to ensure that water will be of the highest quality when it arrives at your tap. From vigilantly testing the water to protecting our distribution pipes and replacing aging infrastructure, LADWP always has your health and water quality in mind. This short video shows you what we do everyday to protect the tap water we serve you.

There are, however, some very important factors beyond the water meter that may affect the water quality in your home. Customers can do many things to greatly improve this. These include disinfecting drains, flushing and disinfecting water heaters, and flushing the plumbing. This short video can show you how.

For more in-depth information, please elect one of the “How To” tabs below on how to maintain or improve water quality at home. In addition, there are also instructions available for treating and storing water in the event of an emergency or natural disaster.

If you have a problem or question that is not addressed below, please call us at 1-800-DIAL-DWP (1-800-342-5397).

    LADWP delivers safe, high quality drinking water from the distribution system to your property’s water meter. Property owners are responsible for the maintenance of property pipe and plumbing to maintain the high quality of water all the way to the tap. Following weeks or months of inactive water use, we recommend flushing your water pipes to clear out possible sitting water and accumulated sediments.

    These are general guidelines to safely and effectively flush plumbing, faucets, toilets and other fixtures on your property. For large commercial properties, please consult your property or building manager.

    1. Prepare site for flushing. Remove aerators and screens from all faucets. Set water softening devices and filters, both point-of-use and whole-house, to the “bypass mode”.
    2. Flush outside plumbing. Open and flush any external fixtures and hose bibs until water is clear and temperature is constant.
    3. Flush cold water. Run all cold water faucets on the property beginning with the faucet closest to the water line. Let all run at the highest flow (or fully open) until water is clear and temperature is constant. Then turn off all faucets in reverse order.
    4. Flush all toilets and urinals. Do this at least once, but repeat if the refilled water is not clear.
    5. Flush hot water. Drain your hot water tank to discharge any accumulated sediments. Wait for the hot water tank to refill and flush as in Step 3.
    6. Clean aerators and screens and reattach to faucets, shower heads, and fixtures.
    7. Flush any water-using appliance or run a cycle. This includes the washing machine, dishwasher, and refrigerator/ice maker.
    8. Restore all removed filters and reset all water devices from bypass mode.

    Maintaining water quality on your property especially after a prolonged shut-off is in accordance with the guidelines of the U.S. EPA’s Information on Maintaining or Restoring Water Quality in Building’s with Low or No Use, Center for Disease Control’s Guidance for Building Water Systems and the International Association of Plumbing and Mechanical Officials' reminders on Rehabilitating Stagnant Building Water Systems.

    LADWP Water Quality Hotline
    (213) 367-3182
    LADWP Water Quality page

    Tap water is typically odorless or may have a slightly chlorinous scent. Sometimes customers may notice the smell of rotten eggs or sewage when using the sink. A perceived odor of rotten eggs or sewage in the water is usually caused by sewer gases forming in the household drain. Sewer gases are formed by bacteria which live on food, soap, hair, and other organic matter in the drain. These gases are heavier than air and remain in the drain until the water is turned on. As the water runs down the drain, the gases are expelled into the atmosphere around the sink. It is natural to associate these odors with the water because they are observed only when the water is flowing. However, the odor is not in the water. The water is actually pushing the odor out of the drain.

    To eliminate this odor, the bacteria in the drain has to be eliminated through disinfection. To disinfect the drain, please follow these seven steps:

    Step Description
    1 Run cold water for 15 seconds into the drain.

    Prepare a 20% solution of liquid chlorine bleach by adding 1 cup of laundry bleach to 4 cups of water.

    Caution: Bleach may cause eye damage, skin irritation, and may damage clothing.

    3 Pour the 20% liquid chlorine bleach mixture down the drain. Pour the bleach slowly around the edges of the drain so that it runs down the sides of the drain.

    If the odor is coming from a sink with a garbage disposal, turn the disposal on for a few seconds while the bleach is being poured. This will disperse the bleach around the inside of the disposal.

    Caution: Take care to avoid splashing while the disposal is on.


    Allow the bleach to remain undisturbed in the drain for about 10 minutes.

    Caution: Prolonged contact with metals may cause pitting and/or discoloration.

    6 After 10 minutes, run hot water into the drain for two minutes to flush out the bleach.
    7 Repeat steps 1 through 6 if the odor returns.

    Caution: Do not mix any drain cleaners or detergents with bleach. Certain combinations can create toxic fumes.

    How to Disinfect a Drain to Eliminate Odors

    Water heaters should be flushed at least once a year to control the build-up of mineral deposits. This will help the water heater operate more efficiently and may help extend the life of the heater.

    Water heaters should also be flushed if you notice the hot water turning a yellowish or brownish color or if it contains a sand-like material. These changes can be caused by the accumulation of rust or mineral sediments.

    The procedure for flushing your water heater is outlined in the following steps:

    Step Description

    Attach a garden hose to the draincock located at the bottom of the heater. The draincock usually looks like a regular hose bib (garden faucet) or a round dial with a threaded hole in the middle.

    Note: Do not shut off the gas or the water supply to the heater.

    2 Extend the garden hose to a place where the water can safely exit the heater (e.g. a drain, a driveway)

    Open the draincock to allow the water to exit the heater.

    Caution: If the draincock is made of plastic and the heater is several years old, it may be difficult to open and may break easily if forced.

    Caution: The water draining out will be hot and under normal household water pressure.

    4 After five minutes of flushing, fill a bucket with the flushing water.

    Allow the water in the bucket to stand undisturbed for a minute and see if the water is clear or if any sand-like material settles to the bottom. 

    • If the water is clear and no sand-like material is observed, go on to step 6.
    • If the water is discolored and/or sand-like material is observed at the bottom of the bucket, repeat steps 4 and 5 until the flush water is completely clear and free of sediment.
    6 Close the draincock and remove the garden hose.


    Illustration of a hot water heater shower cold water in and hot water out.

    If you do not feel comfortable doing this work yourself, please hire a licensed plumber.

    How to Flush a Water Heater

    A foul, bleachy or chemical taste and odor in the water is commonly caused by an accumulation of organic material in the plumbing. Chloramine is a disinfectant added into the water by LADWP to control bacterial growth. It can react with organic material to create disinfection by-products (DBPs). Many of these DBPs have a very strong chemical or bleachy taste and odor.

    The accumulation of organic material can be eliminated by flushing your water pipes. This procedure is outlined in the following steps:

    Step Description

    Remove the screens (aerators) from the ends of the indoor faucets and run all of the faucets at full capacity and simultaneously for 5 minutes.

    Note: Removing the aerators before flushing will allow material dislodged by flushing to pass through the faucet and not accumulate on the screen.


    Flush the toilets two or three times each while the faucets are running.

    Note: Running all the water faucets and toilets simultaneously generates a large flow of water through the pipes and will likely dislodge any build-up of organic material that is causing the taste and odor problem.

    3 After 5 minutes of flushing, turn off the water faucets, clean the aerators, and reinstall them on the ends of the faucets.


    How to Flush Your Household Pipes

    A sulfurous or rotten egg-like odor is usually caused by bacteria growing in the water heater. Bacterial growth occurs:

    • when the water heater is turned off or not in use for an extended period of time
    • when the temperature setting on the heater is set too low

    The bacteria in the water heater does not pose a health threat, but it must be eliminated to correct the odor problem. Heat disinfection is one procedure for eliminating bacteria. This procedure is outlined in the following steps:

    Step Description

    Perform steps 1-9 during the time of day when hot water is not likely to be used for an extended period, such as the evening.


    Turn the thermostat on the water heater to the off position. Only the pilot light should remain lit.

    Caution: If the heater is drained while the heating flame is on, the heater may be damaged.


    Turn off the water supply to the water heater using the valve near the inlet.

    Note: If your water heater does not have this valve, the water supply to the entire property will need to be shut off at the wheel valve.


    Attach a garden hose to the draincock located at the bottom of the water heater.

    Note: The draincock usually looks like a regular hose bib (garden faucet) or a round dial with a threaded hole in the middle.

    4 Extend the garden hose to an appropriate place (e.g., drain, driveway).

    Turn on one or more hot water faucets inside the house.

    Note: This accelerates draining of the water heater by allowing air to enter (per Step 6).


    Open the draincock and allow all of the water to drain out of the water heater.

    Note: This can take anywhere from 5 to more than 30 minutes.

    Caution: The water draining out will be very hot.
    Caution: If the draincock is made of plastic and the water heater is several years old, it may be difficult to open and may break easily.

    7 When the water heater is empty, close the draincock and remove the garden hose.

    Turn the water supply to the water heater back to the on position. Keep the hot water faucet(s) inside the house on as well.

    Note: This will allow the air in the water heater to escape as it refills with water. There will likely be “hissing” sounds and/or “spitting and sputtering” as air and water begin coming out of the hot water faucets. When the water flow from the faucet(s) have steady flow, shut them off.


    Turn the thermostat for the water heater to its highest temperature setting for 6-8 hours.

    Caution: Make sure everyone who uses the water is aware that the hot water is going to be hotter than usual.


    Perform steps 10-11 after heating for 6-8 hours.

    10 Drain and refill the water heater by repeating steps 1 through 8.
    11 Return the thermostat on the water heater to the normal setting (usually around 130° F).


    Illustration of a hot water heater shower cold water in and hot water out.

    If you are uncomfortable doing this work yourself, contact a licensed plumber instead.

    How to Heat Disinfect a Water Heater

    Unsafe Water Alerts

    During an emergency, such as a major earthquake, LADWP may issue an “Unsafe Water Alert” until it is verified that the water is not contaminated and is safe to drink. During an Unsafe Water Alert, follow the instructions as described in the notice.

    How to Store an Emergency Water Supply

    Tap water can be stored in storage containers for emergency use. To create an emergency water supply from tap water, storage containers must first be sterilized and the water must be treated before it is stored. The stored water should be changed every six months. This process of sterilizing containers, treating and storing the water is outlined below:

    1. Choosing the Container 

      To store an emergency water supply, begin by choosing food-grade containers made of heavy opaque plastic with screw-on caps.

      Do not use the following:

      • Plastic milk and juice containers, which are usually very thin and tend to crack and leak as they get old.
      • Containers with snap-on caps, which do not seal as well as screw-on caps.
      • Containers that previously have been used to hold liquid or solid toxic chemicals (e.g., bleach, pesticides, etc.)
      • Glass containers
    2. Cleaning and Sanitizing the Container
      1. Wash the containers with soapy water, then rinse thoroughly.
      2. Fill the container half full with water and add 1 cup of chlorine bleach for each gallon the container holds. Caution: Do not use scented laundry bleach, powdered bleach, or swimming pool chlorine. These contain additional chemicals that are poisonous.
      3. Finish filling the container with water (all the way to the top). Put the cap on and lay the bottle on its side for about 3 minutes. This allows you to check if the container leaks while the bleach-water solution disinfects the cap. If the container leaks, do not use it.
      4. Pour out the bleach-water solution into the next container to be sterilized. The same disinfecting bleach-water solution can be used for several containers – simply “top off” the new container with water as needed. Caution: Remember to pour the bleach-water solution down the drain when finished – this is not drinking water.
      5. Allow the empty sanitized container to air-dry before use or rinse with tap water.
      6. Fill the bottle with tap water. Leave a small air space at the top of the container to allow for expansion if the water heats up slightly where you store it.
      7. Put the cap on tightly.


    3. Storing the Water
      1. Label the container as “drinking water” and include the preparation date.
      2. Keep water stored at a cool temperature (50-70°F).
        • Do not store the water as follows: 

           -In direct sunlight

           - In extreme temperatures

            - In areas where toxic substances (e.g., fumes of petroleum products, pesticides/herbicides, etc.) are present.

      3. Check the containers periodically to ensure that the plastic has not cracked or developed leaks. If the containers are cracked or leak, the containers will need to be replaced.

        Note: Change the water in the containers every six months.

    Single Use Plastic Water Bottles

    As an alternative, bottled water purchased at grocery stores can be used as an emergency water supply. The bottles should be stored in a location without exposure to sunlight, extreme temperatures, fumes of petroleum products, and pesticides/herbicides. Check the bottles periodically to ensure that the plastic has not cracked or developed leaks. If the containers are cracked or leak, the bottles will need to be replaced.

    How to Treat and Store Water for an Emergency