Water Quality FAQs

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PWP Water Service

How much water is used daily in Pasadena?
PWP customers use, in total, approximately 27 million gallons of water each day.

Is Pasadena’s water safe to drink?
Yes. The water delivered to your water meter meets all state and federal drinking water standards and is safe to use without further treatment. However, you are responsible for plumbing and treatment devices installed on your property. Substandard, illegal, old, poorly maintained or improperly installed plumbing or water treatment devices may adversely affect your water quality.

How does PWP test the water?
PWP is required by state and federal law to regularly test the water. We have a crew of state-certified field and laboratory personnel who sample and test the water every day. There are over 100 different constituents in the water that are tested by PWP. The amount of each constituent allowed in the water and the frequency with which we test for each constituent is regulated by the California State Water Resources Control Board Division of Drinking Water (DDW) and by the United States Environmental Protection Agency (USEPA).  Review our annual Consumer Confidence Report on Water Quality to learn more about the stringent testing and water quality guidelines PWP meets each year.

How can I have my water tested?
If you have a specific concern (e.g. lead contamination from your plumbing), or you would just like to verify our test results, services for water testing are available from commercial and environmental laboratories for a fee. The fee depends on the number of constituents you would like tested in the water. A simple lead test will usually cost around $30-$50. If you would like to test your water for everything that PWP tests for, it will easily cost over $1,000. You can obtain references for qualified laboratories by contacting the California State Water Resources Control Board Division of Drinking Water.

Do water filters work and should I use one?
As with most products, some filters work better than others. If you install a water filter, follow the operating and maintenance instructions very carefully. An improperly installed and/or maintained filter can adversely affect the water quality. There are many types of filters available, each type works differently and will remove different substances from the water. It will be very helpful for you to know exactly why you want to filter the water before you speak to a seller of water treatment devices.

If you choose to filter your water, there are several resources available to assist you in choosing a filter that works properly and will meet your needs. Visit the National Sanitation Foundation's website for a list of approved water treatment devices.

Why is disinfectant added to the water?
Disinfectants, such as chlorine and chloramine, stop bacteria from growing in pipelines. PWP uses disinfectants where necessary throughout the water system.

What can I safely pour down the sink or into the toilet?
If your home is on a municipal sewage system, the following can be safely poured down a drain, followed by a flush of water: disinfectants, rust removers, hair relaxers, water-based glues, drain cleaners, aluminum cleaners, window cleaners, and photographic chemicals. A hazardous waste contractor should dispose of all other liquid home products. A similar type of list has not been developed for homes with a septic tank. Contact the Department of Public Works to get information on the disposal of specific products.

What are the causes of low water pressure, and should low water pressure concern me? 
Temporary low pressure can be caused by heavy water use in your area such as a great deal of lawn watering, a water main break, fighting a nearby fire, or by clogged fixtures. Low pressure could be caused by the location of your home - on a hill or far from the booster pump plant, or near a pressure reducing station. The City maintains pressures well above the State's minimum requirements, but can vary from home to home.

Low pressure is more than just a nuisance. The water system depends on pressure to keep out any contamination. If the pressure drops, the possibility of pollution entering the drinking water increases. Learn more on our Troubleshooting webpage. Report any permanent drop in water pressure to PWP by calling our water emergency hotline at 626.744.4138.

My water faucet drips a little; should I bother to fix it? 
Yes. Drips waste a precious product, and this waste should be stopped, even though the dripping water may not register on your water meter. To find out how much water you are wasting, put a measuring cup under the drip and find out how many minutes it takes to fill it up. Divide 90 by the number of minutes it takes to fill one cup to get the number of gallons of water wasted each day.

How does PWP know how much water I use in my home? 
Most households have a water meter that measures the amount of water used in the home. The water meters are read automatically on a regular schedule. The previous reading is subtracted from the current reading to determine the amount of water actually used.

How does PWP know that my water meter is accurate? 
PWP has programs to routinely test water meters. This is done on a rotating basis to make sure the meters are accurate. If your recorded water use changes suddenly for no obvious reason, report this to PWP so it can be investigated. Note that additional people in the home, a sprinkler leak and/or excessive lawn watering can make your water bill higher.

Where does the water go when the toilet flushes?
It goes into a sewer pipeline system that flows into the Los Angeles County Sanitation District’s wastewater treatment plant where one of two things will happen following treatment: it will become recycled water for irrigation purposes, or discharged into the ocean.

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Drinking Water

Is it okay to use hot tap water for cooking?
Use cold water instead from the tap. Hot water is more likely to contain rust and lead from your household plumbing and water heater.

To kill germs in my drinking water after an emergency, what should I do?
Boil the water for 5 minutes (use a timer) after it reaches to a full boil on a stove or in a microwave oven. Do not count the time it takes for the water to reach full boiling. This should be done during emergencies only because this process uses a lot of energy and concentrates some chemicals (nitrates) if they are present in the drinking water. However, in an emergency, the advantage of killing the germs outweighs the disadvantage of the slight decline in water quality (concentrating the chemicals).

Why does my drinking water sometimes appear cloudy or milky? 
Air in the water can create a cloudy or milky appearance. The amount of air in PWP's water can be high at times when the local water table is lower than normal. With lower water tables, PWP's wells draw more air into the water when it is pumped out. In addition, turning on a faucet releases pressure in the water piping system, causing hundreds of tiny air bubbles to form. Like the carbon dioxide in soft drinks, the air bubbles will disappear after a few minutes. There are no health impacts from tiny air bubbles in water.

Why does my drinking water sometimes have a reddish or yellowish color? 
Rust in household water pipes or in water pipes under city streets can create the reddish or yellowish color. The rust is a compound of iron and oxygen that is harmless in drinking water but can stain clothes and porcelain fixtures. Some rusty color is most noticeable after pipe repairs or during periods of low water use. Understanding more about your discolored water requires determining if the rust is coming from PWP's pipes or yours. To do this, follow the steps located on our Troubleshooting webpage.

Why does my drinking water taste or smell “funny"?
Water from PWP's groundwater wells, imported water from Metropolitan Water District of Southern California, and purchased water from neighboring water agencies are of high quality. These water sources may taste different because they have distinct mineral contents. While water quality is measured by chemical and biological analysis, taste is determined by mineral content and the disinfectant processes. Taste and odor may vary depending on where water comes from and how it is treated:

  • The taste can come from the mineral content of the water sources.
  • The taste can come from the chlorine or chloramines that is are added to the water to prevent bacteria from growing in water pipelines.
  • The plumbing inside your home can impart a metallic taste to your water.
  • If you only experience the smell when using your hot tap, it may be a chemical reaction occurring inside your hot water heater, and not a problem with the water supply.

If you are concerned about the taste or smell of your tap water, please call Customer Service at 626.744.4005. Learn more on our Troubleshooting webpage.

What can I do if my drinking water taste or smell “funny”? 
Here are few suggestions you can take if you detect a funny taste or smell in your water;

  • Some people are sensitive to the taste and smell of chlorine and chloramine. You may chill water overnight in a glass container in the refrigerator, which helps to dissipate the chlorine compounds.
  • Adding lemon or lime slices to refrigerated water may result in pleasant tasting water.
  • Charcoal filters are also very effective at removing chlorine and chloramine. If you choose to use a filter, follow the operating and maintenance instructions very carefully. An improperly installed and/or maintained filter can adversely affect the water quality.
  • Sometimes hydrogen sulfide located in the plumbing trap underneath the sink can give the illusion of an odor in the water. If the odor disappears when a cup of water is tasted or smelled away from the sink, this could be the cause. Pour vinegar, chlorine bleach, lemon juice or  lime juice down the sink and let it sit for 20 to 30 minutes. Then flush with water for 5 minutes.

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Metropolitan Water District of Southern California (MWD) supplies more than 60% of Pasadena's drinking water. In October 2007, MWD began adding fluoride to their water supply. Before drinking water is delivered to your home or business tap, the fluoridated MWD water will be blended with Pasadena groundwater. Here are answers to frequently asked questions about fluoride in drinking water:

What is fluoride?
It is a naturally occurring compound derived from fluorine, an abundant element in surface water (lakes, rivers & oceans) and groundwater (water from rain that soaks through the soil and into an underground aquifer)

What are the benefits of fluoride? 
According to the Centers for Disease Control and Prevention (CDC), the fluoridation of community drinking water is the most cost effective and safe way to reduce and control tooth decay. More than 50 years of scientific research has led to the conclusion that people who live in communities with fluoridated water have healthier teeth and fewer cavities than those living where water is not fluoridated.

How much fluoride will MWD add to Pasadena's community drinking water? 
MWD's water naturally has 0.1 to 0.4 parts per million (ppm) of fluoride, and is fortified to a final concentration of 0.6 to 0.9 ppm. Pasadena's groundwater has natural fluoride levels of 0.3 to 1.4 ppm, so the resulting concentration is typically around 0.8 ppm in our community drinking water.

How is "parts per million" defined? 
To put it simply, if there are a million "parts" - teaspoons, for example - then 1 part per million equals 1 teaspoon of a substance mixed in with one million teaspoons of water.

What if I don't want to drink fluoridated water? 
Home water treatment units that use reverse osmosis membrane filters can effectively remove fluoride from tap water. Most bottled water does not contain fluoride; check the label to be sure.

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Soft vs. Hard Water

What is hard water?
Hardness in drinking water is determined by the amount of calcium and magnesium it contains. These minerals are harmless, but they can cause temporary white spots on glasses and make soap difficult to lather. Pasadena’s water has an average hardness of 12.9 grains per gallon and it is considered to be very hard. There is no known health effect that is caused by hard water. Like other minerals, calcium and magnesium are beneficial to human health.

Why does my dishwater leave spots on my glassware? 
Harmless minerals that remain on the glass when water evaporates causes the spots on glassware after it is washed and/or air-dried. Commercial products are available that allow the water to drain from the glassware more completely. Spots on glass shower doors appear for the same reason.

How does water become hard? 
Water becomes hard as it passes over or through certain geological formations that contain calcium or magnesium. For example, groundwater becomes hard as it percolates down to the water table though limestone deposits containing calcium, or though dolomite and other magnesium bearing minerals that dissolve in water. Surface water imported to Pasadena is hard because it has passed over similar formations as it flows hundreds of miles from the Colorado River and from the streams in Northern California.

When should you expect hard water in Pasadena?
Because the source of PWP’s water varies at different times of the year, the hardness of our drinking water also varies. We rely on groundwater from our local wells more during the summer months than in other seasons. Additionally, the hardness level of the water we import from the Metropolitan Water District of Southern California will vary depending on how much is coming from the Colorado River vs. Northern California.

How is hard water softened?
Household water softeners typically use salt to reduce hardness in water. As water passes through the softening unit, sodium atoms in the salt replace calcium and magnesium atoms. Some cities have banned the use of water softeners because they discharge a waste that contains large amounts of chloride. Over time, the salt-bearing unit must be changed or recharged to remain effective. In purchasing a water softener, be aware of various recharging procedures, since these vary significantly from model to model. Visit the National Sanitation Foundation (NSF) website www.nsf.org for a list of approved water treatment devices and if you do install a water softener, follow the operating and maintenance instructions very carefully.

What are the advantages and disadvantages of soft water? 
Soft water can help maintain the unobstructed flow in water pipes and extend the life of bathtubs, sinks, and toilets by minimizing the buildup of mineral deposits. It can also reduce soapy films on tubs and shower tiles, promote thorough rinsing of shampoos and soaps, and improve the efficiency of water heaters. Washing clothes in soft water requires less soap. However, excessively soft water can cause corrosion in pipes. In addition, increased levels of sodium in softened drinking water may pose a health consideration for some people on restricted sodium diets.

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PWP Water Supply

Where does tap water come from?
There are two major sources of tap water: surface water, and groundwater. Surface water comes from lakes, reservoirs, and rivers. Groundwater comes from wells that are drilled into aquifers. An aquifer is an underground geologic formation through which water flows slowly.

Where does PWP water come from?
About 40% of the supply is groundwater from the Raymond Groundwater Basin and is pumped out of 10 deep wells located throughout Pasadena. Roughly 60% of the water is imported from the Metropolitan Water District of Southern California (MWD) and consists of a blend of water from Northern California and the Colorado River. In addition, a modest amount of water is purchased from neighboring water agencies that combine surface water and groundwater.

How is the Groundwater in the Raymond Basin replenished?
Rainfall is the main source of water that replenishes the Raymond Groundwater Basin. PWP and other water agencies only pump water out of the Raymond Basin that is equal to what is naturally replenished. During a drought, however, the groundwater levels will slowly drop because there is little to no rainwater or mountain runoff to replenish the basin.

What is the Hahamongna Watershed Park?
The Hahamongna Watershed Park (HWP) is approximately 1,300 acres of open space extending up the Arroyo Seco Canyon from Devil’s Gate Dam. There are four water wells within the HWP basin owned by the City of Pasadena.

What is the Devil’s Gate Dam?
The Devil’s Gate Dam was constructed in 1920 and renovated in 1998. It is used for flood protection and as a water reservoir to recharge the Raymond Basin Aquifer. The Devil’s Gate Dam is owned by Los Angeles County Department of Public Works.

What are the major components of the PWP water distribution system?
PWP has 10 active wells that feed groundwater into various reservoirs. There are 18 reservoirs throughout the city that hold well water and purchased water from the Metropolitan Water District of Southern California. Jones Reservoir, PWP’s largest reservoir, can hold about 50 million gallons of water and Lida Reservoir is the smallest with a 0.43 million gallon capacity. The water is disinfected and blended in the reservoir and then distributed to the customers through a pipeline network of 520 miles of mains throughout the city.

What is being done to protect Pasadena’s water supply from current or future contamination?
PWP conducts sanitary surveys of the Arroyo and Eaton Canyon streams regularly. These streams supplement our groundwater supplies. The Department of Public Works has waste disposal programs so that customers can remove hazardous materials appropriately and not have it end up in our groundwater supplies.

Why can’t ocean water be treated to make drinking water? 
Ocean water can be treated but building and operating a desalination plant and transporting the water to Pasadena would be too expensive. The cost of converting saltwater to drinking water has been estimated at $5 to $7 per 1,000 gallons. Additionally, ocean water is extremely salty and would take a substantial amount of energy to convert it to drinking water.

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Lead and Copper Testing

Does PWP Test for Lead and Copper?

Every three years, PWP is required by state and federal regulations to test the water inside at least 50 homes (number of households tested vary depending on the number of customers served by the water agency) throughout Pasadena to ensure that water from the customer's tap water does not leach lead and copper from the plumbing. Pasadena has been in compliance with the Lead and Copper Rule since it was implemented in the early 1990’s.  Furthermore, the PWP system is already considered to be “optimized” for corrosion control, which means Pasadena’s water does not tend to leach lead and copper from household plumbing.

 What are the Sources of Lead?

Drinking water is one of the ways customers can consume lead. The Environmental Protection Agency (EPA) estimates that less than 20% of lead exposure for the overall population is from drinking water. However, infants who consume mostly mixed formula can receive 40 to 60 percent of their exposure to lead from drinking water. However, the primary sources of lead exposure, particularly for children is actually related to exposure of deteriorating lead-based paint, lead­ contaminated dust, and lead-contaminated residential soil. Lead can occasionally be found in some toys, playground equipment, children’s metal jewelry, and traditional pottery. Other sources include food and beverage containers, leaded gasoline, and occupational exposure.

What are the Health Effects of Lead and Copper Exposure?

 Lead can cause serious health problems if too much enters your body, whether from consumption or other sources. Too much lead can cause damage to the brain and kidneys, and it interferes with the production of red blood cells that carry oxygen to all parts of your body. The greatest risk of lead exposure is to infants, young children, and pregnant women. Scientists have linked the effects of lead on the brain with lowered IQ in children. Adults with kidney problems and high blood pressure can be affected by lower levels of lead more than healthy adults. More information can be found here on the Pasadena Health Department’s Childhood Lead Poisoning Prevention Program.

Copper is an essential nutrient, but some people who drink water containing copper in excess may, with short term exposure, experience nausea, cramps, diarrhea and/or vomiting. Those with long-term exposure may experience liver or kidney damage.

How Can I Reduce Potential Lead Exposure?

Pasadena’s drinking water lead levels are in compliance with the Lead and Copper Rule, but if you are concerned about lead exposure you may still want to consider these steps to reduce potential exposure:

  • Run your water to flush out stagnant water in your plumbing. If water hasn't been used for several hours, run the tap for 15-30 seconds before using it for drinking or cooking.  Avoid wasting water by using it to rinse dishes or water plants.
  • Always use cold water for cooking and preparing baby formula.
  • Please note that boiling water will not remove lead.

For more information on reducing lead exposure around your home and the health effects of lead, visit EPA's Web site at www.epa.gov/lead, or call the National Lead Information Center at 800-424-LEAD. More information about your water is available in the annual Consumer Confidence Report (CCR) on Water Quality. It contains important information on water supply sources, drinking water contaminants, and water quality data for the City of Pasadena.

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What to Do During an Emergency

Water is vital to everyday life, necessary for health and should never be taken for granted. It is very important to be prepared for water emergencies BEFORE they occur. Earthquakes, floods, high winds, droughts and forest or brush fires are events that can create water emergencies. Likewise, broken water mains, power outages, treatment plant breakdowns, and failure of storage tanks or equipment are considered "water system" emergencies.

Learn how to shut off the main water valve to your house. Make sure you know the location of the valve; have the necessary tools to operate it; and mark it with fluorescent paint or tape for locating the valve in the dark.

Purchase bottled water or store water in clean unbreakable containers that can be properly sealed or capped after filling. It is recommended to have at least one gallon of water per person per day (remember to store for pets too), and store enough water for three to five days. Keep water stored in a cool area away from direct sunlight. Water should be replaced every six months.

If you must use tap water during a water emergency, make sure your water has been disinfected by boiling it for 5 minutes or you can use water-disinfecting tablets (4 tablets per gallon), tincture of iodine (12 drops per gallon) or liquid chlorine (8-10 drops per gallon). After treatment, mix the water thoroughly and let it stand for 30 minutes before use. If the water has been chemically polluted, these methods will not make your water safe: Do not use this water.

For more information about how to prepare for an emergency click here.