It depends on who bills you. The City of Surprise delivers only groundwater, pumped from the West Salt River Valley sub-basin by 19 wells. Some Surprise addresses are served instead by EPCOR, which draws on the Central Arizona Project, Lake Pleasant and groundwater, or by Liberty's Beardsley Water Company 1, which pumps groundwater.
Which utility serves your address?
Three utilities appear in the records for Surprise. The City of Surprise runs its own system. EPCOR says it provides water service to "certain residents of the City of Surprise" under a Certificate of Convenience and Necessity from the Arizona Corporation Commission. And Liberty's water safety page lists "Surprise: Beardsley Water Company 1" among its reports.
You can tell which one is yours in about a minute. Look at the name on your water bill. If you rent or the water is bundled in, ask the landlord or HOA who the provider is. EPA also lets you look up your utility's annual report through its CCR search tool, and the City of Surprise water pages include a "Find your Drinking Water Provider" page.
What the City of Surprise delivers
The city's 2025 reports say that "ALL OF THE WATER PROVIDED BY THE CITY OF SURPRISE COMES FROM GROUNDWATER PUMPED FROM THE WEST SALT RIVER VALLEY (WSRV) SUB-BASIN." The city owns and operates 19 wells. That groundwater goes to six water supply facilities, four of which provide arsenic removal treatment, and all of which disinfect it. The city pumped 10,913.18 acre-feet in 2025, which it equates to 3,556 million gallons.
The city publishes a separate report for each of three systems: Mountain Vista, Desert Oasis and Surprise Foothills. Their 2025 numbers differ a little:
| City system | Average hardness, 2025 | Arsenic, 2025 (EPA limit 10 ppb) |
|---|---|---|
| Mountain Vista | 3.9 grains per gallon | 5.3 ppb |
| Desert Oasis | 6.2 grains per gallon | 6.1 ppb |
| Surprise Foothills | 5.3 grains per gallon | 4.0 ppb |
Those hardness averages sit well below Phoenix, whose 2025 report lists 10 to 17.6 grains per gallon. Desert Oasis samples ranged from 2.6 to 11.11 grains per gallon in 2025, though, so even within one system a single reading does not tell the whole story.
On supply security, the city's 2024 notice about the Colorado River shortage says "Due to Arizona's priority system, our city supplies will not experience a reduction," and describes a portfolio of "renewable surface water, groundwater and reclaimed water." What comes out of a city tap, per the 2025 reports, is still groundwater.
What EPCOR customers get
EPCOR's 2025 Agua Fria report lists three sources: the Colorado River via the Central Arizona Project (CAP), Agua Fria River water captured behind the Waddell Dam at Lake Pleasant, and groundwater from the West Salt River Valley sub-basin. Because the supply mixes surface water and groundwater, EPCOR warns that you may notice seasonal changes in hardness and taste, which it calls normal and safe.
Hardness is the big difference. EPCOR reports 2 to 17 grains per gallon across that system in 2025. By EPCOR's own scale, 3.5 to 6.9 is moderately hard, 7 to 10.4 is hard, and above 10.5 is very hard. So an EPCOR address could land anywhere from the city's range to Phoenix-level hardness.
One caution: EPCOR operates several districts, and its Surprise page does not say which district report covers which street. Confirm with EPCOR (the number is on the report) before you use a hardness figure to set a softener.
What Liberty's Beardsley Water Company 1 customers get
Liberty's 2025 report for Beardsley Water Company 1 says its drinking water "comes from the Western Valley Salt River Aquifer," drawn from the middle and lower alluvial units about 200 to 600 feet down. Hardness ran 2.2 to 5.1 grains per gallon in 2025, averaging 3.7, and the report states the system had no violations of federal or state safe drinking water standards in 2025.
Why the source matters at your faucet
Source tells you what to expect from scale. Phoenix's report notes that hard water can cause scaling in pipes and water heaters and on fixtures such as faucets and showerheads. Harder water generally means more scale. A home at the high end of EPCOR's range has a very different scale problem than a Mountain Vista home at 3.9 grains, and that gap is what decides whether a softener is worth considering. Our page on how hard Valley water is by city puts the central Valley numbers next to these, and why hard water damages plumbing explains the wear.
Arsenic is the other number worth knowing. The city treats for it at four of its six facilities, and its three systems each reported an annual arsenic level below the EPA limit of 10 ppb in 2025. For the health background, see arsenic in Arizona drinking water, and for how to read any of these reports, see how to read your tap water quality report.
Before you size or program a softener, test hardness at your own tap, because a system average is not a measurement of your house. If you are weighing a softener, our water softening service page covers what installation involves, and a licensed plumber can check your pressure and fixtures at the same visit. Planning plumbing work in Surprise? See what we cover on our Surprise service area page.