Water Quality Summary of Water Supply Sources

The information in this table is based on water quality monitoring results for the most recent 16-month period.

Water Quality Measure	Tucson Supply Source
	Clearwater	Avra Valley Wells	Santa Cruz Wells	Central Wells	South Side / TARP
Chlorine, mg/L	1.03	In Progress	In Progress	.86	.89
Fluoride, mg/L F	.42	In Progress	.43	.28	.64
Hardness, mg/L CaCO3	213	In Progress	In Progress	In Progress	216
Nitrate as Nitrogen, mg/L N	.93	In Progress	2.6	3.69	2.26
Sodium, mg/L Na	63	In Progress	In Progress	43	63
Temperature, deg.F	81.3	In Progress	73.2	74.9	77.3
Total Dissolved Solids, mg/L	470	278	468	376	441
pH, Std. Units	7.81	In Progress	7.38	7.6	7.93

• Water supply source data is being collected for all points at this time. 'In Progress' indicates that the data is under development and will be included in the table as the data becomes available.
• Chlorine residual measures the free available chlorine in drinking water. Chlorine is used to maintain continuous disinfection throughout the distribution system. The EPA's maximum limit for chlorine residual is 4.0 mg/L on average. In order to ensure your drinking water is protected, Tucson Water's chlorination goal is to maintain a detectable level of chlorine at all times throughout the system.
• Fluoride is a naturally occurring constituent in drinking water. The drinking water standard for fluoride is 4 mg/L on average. The optimum fluoride level for drinking water is 0.8 mg/L. Where the fluoride level of drinking water is less than 0.6 mg/L, supplements may be worthwhile depending on the individual situation. Please see your medical provider.
• Hardness is the measure of calcium and magnesium in drinking water. Hardness levels in Tucson's water vary from around 40 to more than 300 mg/L CaCO3. (If you have a water softener, you can calculate the grains per gallon of hardness by taking the mg/L value and dividing by 17.1)
• Nitrate as Nitrogen can occur in drinking water supplies from both natural sources and human activities (such as fertilizer use, munitions manufacturing, and septic systems). The EPA's health-based limit for nitrate as nitrogen in drinking water is 10 mg/L - all of Tucson's water supplies have nitrate as nitrogen levels below this limit.
• Sodium is a naturally occurring constituent in drinking water, and typically originates as water dissolves rocks and soils as it flows in streams and rivers or percolates underground. A sodium content of 20 mg/L or less in drinking water meets EPA's guideline for 'sodium-free' diets.
• Total dissolved solids (TDS) is a measure of the mineral content of drinking water. There are no health-based limits for TDS in water.
• Temperature is the water temperature in Tucson's distribution system. This typically ranges from 60^o to 90^o F over the course of the year.
• The pH of a water measures the water's balance of acids and bases. A pH of 7 is considered neutral with lower pH values representing an acidic water and higher pH values representing a more basic or alkaline water. Tucson's water supply is slightly alkaline, averaging between 7.5 and 8.2 in the distribution system.
• For more information on water quality, see our Terms and Definitions page.