City of Santa Rosa > Departments > Water > Water > Water Quality
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Water Quality

What is a drinking water quality report? Water suppliers must deliver to their customers an annual drinking water quality report or consumer confidence report (CCR). This report will tell consumers what contaminants have been detected in their drinking water, how these detection levels compare to drinking water standards, and where their water comes from.

2014 Water Quality Report Now Available (Click Here)

View this year's Water Quality Report, reflecting on 2014’s water quality monitoring results. Other topics include Important Health Information, water sources and general information about Santa Rosa’s drinking water. For past years' reports, check the "Water Quality Links" to the left.

Arsenic Detection - Arsenic is rarely detected in Santa Rosa's water. We did, however, have a detection in 2014 but it may have been the result of sample bottle contamination. Please review our statement on arsenic (click here).

Where does tap water come from? The raw water for drinking water purposes starts as either surface water or groundwater. Surface water is just what the name implies; it is water found in a river, lake or other surface impoundment. Groundwater is that which is trapped beneath the ground. Rains that soak into the ground and rivers that disappear beneath the earth are a few of the sources that recharge the supply of underground water.

Groundwater wells near the Russian River provide the bulk of Santa Rosa’s water supply. The City, however, has two very deep wells that provide 2.5 million gallons per day of our 27 million gallon per day summertime requirements. The City’s two groundwater wells only operate from April to November of each year.

Why is the drinking water stored in large tanks on hillsides? This type of water storage ensures that water pressure and water volume are stabilized and provides sufficient water supply to fight fires, even if the electricity that normally pumps water is turned off. 

What is the best choice of drinking water: bottled or tap water? Tap water because our water is of excellent quality, carefully monitored, and affordable.

When we look at issues such as quality, monitoring and affordability, we see that bottled water doesn't always measure up. Some brands of bottled water may be of excellent quality, but others can have inferior quality or they may be simply taken from municipal water supplies. All of the bottled waters are more expensive than tap. For the price of one small bottle of water, you would be able to buy about 340 gallons of tap water. 

There are also fewer government regulations to guide the bottled water industry. Monitoring requirements aren't as stringent as are those for tap water. For quality, consistency and affordability, tap water is the better choice.

My tap water sometimes has an odd taste and odor. Why? Usually taste or odors are caused by on-site effects at the home or business. Water heaters can impart odd odors, and if a garden hose is attached and pressurized, it can cause odors at the tap. If your home is on a cul-de-sac or dead-end street, sometimes the water main does not circulate and can cause odors. Aesthetic characteristics generally do not pose a public health threat.

Chlorine or chemical tastes or odors are usually caused by the addition of chlorine to the water.  

What can I do to avoid taste and odor in my tap water? Although harmless, it can affect the taste and smell of your drinking water even at very low concentrations. The best way to reduce taste and odor is to run the faucet for several minutes, put some water in a container, and/or refrigerate it before drinking.  

Is my tap water safe to drink? Yes. We test our drinking water continuously to assure quality. We meet or exceed health-based standards for tap water quality.

Does Santa Rosa fluoridate its drinking water? No. We do not add fluoride to the tap water. Santa Rosa Water's average naturally-occurring fluoride level was so low we could not detect it this year. The optimal fluoride level recommended by the American Dental Association (ADA) is 0.7 ppm. You may want to consult your dentist about ways to prevent tooth decay. For more information about fluoridation, oral health, and current issues, visit the website for the County of Sonoma, Department of Health Services: sonoma-county.org/health/topics/fluoridation.asp.

Is fluoride in my drinking water safe? Yes. This naturally present fluoride in drinking water is below the Maximum Level of 2.0 mg/L set by the US EPA.

What is water hardness? Water hardness represents total concentration of calcium and magnesium ions, reported as calcium carbonate.  

Water Hardness Scale

Grains Per Gallon

 Parts Per Million (ppm)


less than 1.0

less than 17.1


1.0 - 3.5

17.1 - 60

Slightly Hard

3.5 - 7.0

60 - 120

Moderately Hard

7.0 - 10.5

120 - 180


over 10.5

over 180

Very Hard

What are the health effects associated with hard water? Hard water is not known to cause any adverse health effect.

What is the conversion factor for mg/L of hardness to grains per gallon of hardness? One grain per gallon of hardness is equivalent to 17.1 mg/L (calcium carbonate equivalent).

How to set your water softener correctly? If you decide to purchase a water softener, you need to set it according to the hardness of the tap water. Average hardness for Santa Rosa’s water is 6.0 grains per gallon. Also, iron is below detection levels. 

What is the white residue on pots and pans after I boil water? Santa Rosa tap water is Moderately “hard.”  (See the illustration above.)  Groundwater sources contain calcium and magnesium hardness. The minerals in the water leave a conspicuous white residue or spots when water is boiled or evaporates. This residue is primarily calcium and is not harmful to human health. 

If I am on a salt-restricted diet, will the sodium in drinking water hurt me? No, for an individual on a restrictive sodium diet who consumed two liters of water daily, our drinking water would account for no more than 2.7% of the allotted sodium budget, based on 1,500 mg per day. 

What are total coliform bacteria? Total coliforms are a group of closely related bacteria that are (with few exceptions) not harmful to humans. They are natural and common inhabitants of the soil and ambient waters (e.g., lakes, rivers, and estuaries), as well as the gastrointestinal tracts of mammals.

What is E. coli? Where does it come from? How can water be treated to protect against E. coli? E. coli is short for Escherichia coli. E. coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. E. coli comes from human and animal wastes. During rainfalls, snow melts, or other types of precipitation, E. coli may be washed into creeks, rivers, streams, lakes, or groundwater. When these waters are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water. The water can be treated using chlorine, ultra-violet light, or ozone, all of which act to kill or inactivate E. coli. Santa Rosa’s water is naturally filtered and properly treated to eliminate E. coli.

How often do you test tap water for total/fecal coliform? Every week we test tap water for presence/absence of coliforms. We also collect at least 120 samples each month at the representative sites throughout the City’s distribution system. The City has its own water quality lab certified through the State Water Resources Control Board, which performs bacteriological analysis of coliform, implementing EPA-approved methods in-house. The absence of total coliforms in the distribution system minimizes the likelihood that fecal pathogens are present. The total coliforms are used as indicators to determine the vulnerability of a system to fecal contamination.

Why is water tested for total/fecal coliform only? EPA considers total/fecal coliform as useful indicators for the pathogens. Presence or absence of total coliforms determine the adequacy of water treatment and integrity of the distribution system.

What can cause the tap water to be cloudy or milky? Cloudy water commonly is caused by air in the water. If the cloudiness does not dissipate when the water is allowed to stand for a few minutes, the cloudiness may be due to some other cause. To help determine the cause(s) of cloudiness of your drinking water, please notify the Water Quality Division at 707-543-3965.

Glasses of Water with differnent levels of Cloudiness

What can cause tap water to smell like bleach? Chlorine used for disinfection of drinking water may produce a bleach odor in the tap water.

Sometimes water coming out of my tap is brown or has sediments in it. Why? This is caused by sediment in the water mains that is disturbed by fire hydrant use or water main line flushing. Illegal use of fire hydrants can cause severe damage because the inexperienced user opens or closes the valve too fast. This can cause a water hammer which, at the very least, can cause colored water. A water hammer has been known to blow fire hydrants out of the street.

What should I do if I turned on a faucet and the water coming out is discolored? Do not be alarmed. Run your faucets for about five minutes to make sure the water is clear. If the water does not clear within a few minutes, please notify the Water Quality Division at 707-543-3965.

What is wrong if I smell a rotten egg odor when I run water in the house? The smell of rotten eggs indicates the presence of hydrogen sulfide. The odor originates as sewer gas being displaced from the drain when the tap is run. A simple test is to fill a glass of water, take it to a room that has no water, and then sniff the water. If the water no longer has an odor, the drain is the source. A remedy for cleaning the drain is to pour one-quarter cup baking soda down the drain and follow it with a cup of vinegar. When the mixture fizzing stops, flush the drain with boiling water. 

Does the City of Santa Rosa test private well water? The City of Santa Rosa does not test private well water. The Public Health Division of the County of Sonoma may be able to provide this service. You may contact them by phone at 707-565-4711. You may also find water testing companies in the Sonoma County Yellow pages under Laboratories-Analytical. 

For additional questions, please contact the Water Quality Division at 707-543-3965 (Monday through Thursday 8am-5pm and every other Friday, 8am-4:00pm). 


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