How hard is the water in Phoenix?

Phoenix water has a hardness level ranging from 9-20 GPG (158-344 PPM), with a typical average around 15 GPG. This is classified as "Very Hard" by USGS standards. The wide range is due to blending different water sources throughout the year and across different zones.

Where does Phoenix get its water?

Phoenix water comes from three main sources: the Salt and Verde Rivers (via Salt River Project reservoirs), the Colorado River (via the Central Arizona Project canal from Lake Pleasant), and local groundwater wells. The blend varies by season, location, and demand—summer months typically see more groundwater, which is harder.

Is Phoenix hard water safe to drink?

Yes, Phoenix water is safe to drink. The City of Phoenix Water Services conducts over 5 million tests annually and meets or exceeds all EPA and state safety standards. Water hardness (calcium and magnesium) poses no health risks and actually contributes minor dietary minerals. The high Total Dissolved Solids (560-686 ppm) exceeds the aesthetic guideline but isn't a health concern.

Do I need a water softener in Phoenix?

With water hardness averaging 15 GPG and reaching up to 20 GPG in some areas, a salt-based water softener is highly recommended for Phoenix homes. Hard water causes scale buildup in pipes and appliances, reduces soap effectiveness, and can significantly shorten the lifespan of water heaters. A 48,000-grain capacity unit is recommended for a family of four.

Why does Phoenix water taste different at different times of year?

Phoenix water taste and feel changes seasonally because the city blends water from different sources. In fall, algae blooms in canals release Geosmin compounds that cause an earthy/musty taste (harmless but noticeable). Summer peak demand increases groundwater usage, making water harder. The city uses activated carbon to mitigate taste issues but complete elimination during blooms is difficult.

Are water softeners restricted in Phoenix?

Unlike Scottsdale, Phoenix does not have strict water softener restrictions. However, Arizona is moving toward requiring high-efficiency (demand-initiated) softeners rather than time-clock models to reduce salt discharge into the wastewater system. Some HOAs may have their own rules, so check before installing.

Water Hardness in Phoenix, Arizona

Official water hardness data from the City of Phoenix Water Services

Hardness Level

15 GPG

250 PPM (avg)

Classification

Very Hard

Water Source

Multiple

Salt, Verde, CAP, Wells

Last Updated

May 2024

CCR Report

What This Means For You

Phoenix has some of the hardest water in the United States, with levels ranging from 9 to 20 GPG depending on your location, the season, and which water sources are being blended at any given time. Water is classified as "very hard" when it exceeds 10.5 GPG—most Phoenix residents experience water well above this threshold.

Phoenix water comes from a blend of three surface water sources—the Salt and Verde Rivers (via Salt River Project) and the Colorado River (via Central Arizona Project canal)—plus groundwater wells. The blend varies seasonally and by location. Water flows through limestone and dolomite formations in the mountains, and gypsum deposits along the Colorado River, picking up calcium, magnesium, and sulfates that create the high hardness levels.

While hard water is completely safe to drink (calcium and magnesium are essential minerals), it causes significant practical problems: scale buildup in pipes and water heaters can reduce efficiency by up to 29%, spotty dishes and fixtures, dry skin and hair, and the need for more soap and detergent. In the hot Arizona climate, evaporative coolers and misting systems are particularly vulnerable to scale damage.

Mineral Composition

Sodium

143 mg/L

Total Dissolved Solids

623 mg/L

Alkalinity

175 mg/L

Note: Phoenix water has high TDS (560-686 ppm), exceeding the EPA's aesthetic guideline of 500 ppm. This can accelerate corrosion and affect ice makers.

Hardness by Area

Central/North PhoenixVerde River blend zones tend toward lower end: 9-12 GPG

South PhoenixHigher CAP/groundwater mix can reach 18-20 GPG

West PhoenixLake Pleasant (CAP) storage zones: 15-18 GPG typical

Summer monthsGroundwater injection increases hardness toward 20 GPG

Frequently Asked Questions

Official Source

Data sourced from the official Consumer Confidence Report published by the City of Phoenix Water Services.

View Official Water Quality Report →