Filling a Pool in Glendale: Your Tap Water’s Starting Numbers
Filling a pool in Glendale means starting from City of Glendale Water Services Department’s water — which is very hard at roughly 229 mg/L total hardness (about 13.4 grains per gallon). Here is what those published numbers actually do to a pool — and what they do not.
Which way this water pushes a pool
At a typical 84 F pool temperature the published City of Glendale Water Services Department numbers index at +0.40 — inside the balanced band (how this is calculated). That puts Glendale 9th of the 15 cities here that publish enough to compute an index, counting from the most scale-forming down.
Since utilities publish TOTAL hardness and the index wants the CALCIUM fraction, +0.40 is a ceiling and the true figure sits at or below it — which for a near-balanced reading means Glendale water can test slightly aggressive once it is in the pool. Worth knowing before you assume balanced water needs nothing.
The top-off arithmetic
Evaporation removes pure water and leaves the minerals behind, so make-up water re-adds Glendale hardness every time. Replacing one full pool volume through top-off adds roughly another 229 ppm; starting from a fresh fill at about 229 mg/L, that reaches the 400 ppm ceiling after about 0.7 pool volumes of make-up water — less than one full pool volume — a hot-summer pool can work through that in a season or two, not decades. That is the 10th shortest budget of the 27 cities in this lookup.
Evaporation-only and deliberately the fastest case: splash-out, backwash and rain all dilute, and this uses published total hardness rather than the calcium fraction a kit reads (how this is calculated).
How much your own tap may differ
City of Glendale Water Services Department reports hardness spanning 153 to 309 mg/L — a 2.0x range end to end. That is not measurement noise. It is what blending different sources into different service zones does over a year, and it means the single number at the top of this page is an average your own tap may not match. A pool a few neighbourhoods away can legitimately fill at a different hardness than yours. Test what comes out of your hose; do not plan off the midpoint.
Why Glendale water is like this
Glendale’s minerals come from the same two-watershed story as its neighbors – snowmelt and monsoon runoff crossing desert geology – but Glendale has a structural quirk that drives variability: its SRP entitlement is tied to LAND, not to the whole city. SRP provides supply for demand on Glendale’s approximately 15,000 acres of SRP-ELIGIBLE LANDS at a normal allocation of 3.3 acre-feet per acre per year. Property outside that eligible acreage is served from the CAP/Colorado and groundwater side instead.
So which river’s minerals are in your fill water is partly a function of a historical land entitlement boundary, not just of which plant is closest. The other Glendale-specific factor is the disinfectant: Glendale uses CHLORINE DIOXIDE GAS at the treatment plant rather than straight chlorine, specifically to reduce formation of trihalomethanes. That is a real difference from a chloraminated or free-chlorine system and changes what a pool owner is actually adding to the pool on fill day.
Glendale also warns that during drought years SRP may reduce the amount of water delivered per acre or CHANGE THE TYPE OF WATER IT DELIVERS (shifting from reservoir surface water toward SRP well groundwater), which would move fill chemistry without any change at the customer’s end.
Chlorine dioxide gas is used as the disinfectant at the water treatment plant instead of chlorine, to reduce formation of cancer-causing compounds such as trihalomethanes. Glendale documents a well-known side effect: small amounts of chlorine dioxide diffusing into indoor air combine with household VOCs to produce odors described as fuel oil, kerosene or cat urine, most noticeable after new carpet, upholstery or interior painting, with no identified health concerns.
An activated carbon filter removes chlorine dioxide and other chlorine compounds. No softening step is documented. Glendale analyzed more than 19,000 water samples in the prior year and tests for more than 120 substances.
Both, and Glendale documents each. SEASONAL: the city states directly that tap water tastes different throughout the year due to seasonal environmental changes, in part from growth of harmless algae in its lakes and canals during hot weather, and that it cannot always eliminate these fluctuations. It also warns SRP may change the TYPE of water delivered (surface vs well) during drought years.
ZONAL: Glendale is divided into four different PRESSURE zones, and separately its SRP entitlement covers only about 15,000 acres of SRP-eligible land, with the Cholla and Oasis plants taking the SRP side; secondary reporting indicates Cholla serves Water Zones 1 and 2, but that zone-to-plant mapping was NOT confirmed on a Glendale primary source and should be treated as unverified. Glendale publishes no hardness-by-zone table.
NOTE: Glendale’s 2025 Water Quality Report was still listed as ‘Coming Soon – available July 2026’ when checked on 2026-08-14, so the most current CCR was not retrievable.
Background sources: glendaleaz.gov, azmet.arizona.edu.
Before you drain or refill in Glendale
Strong, with exact code citations, and a documented pool-fill sewer appeal. DRAINING: Glendale’s ‘How to Drain and Backwash Pools Legally’ guidance says to irrigate landscaping with the water where possible and NOT to drain into the street, alleyway or other city right-of-way. For large volumes use the home’s sewer clean-out; maximum recommended discharge rate is 12 gallons per minute, less depending on drain line size, distance to the sewer main and pipe condition.
It warns that wall-type clean-outs risk backing water into the home and that most pool filter pumps discharge too fast, recommending a submersible pump of about 700 gallons per hour.
CODE CITES: Glendale City Code section 30-4 prohibits discharge of water into any street, sidewalk or alley in such quantity as to create flooding, impede vehicular or pedestrian traffic, cause damage, create hazardous traffic conditions, or constitute a threat to public health or safety; and section 25-24(e) states that NO PERSON SHALL PERMIT THE DISCHARGE OF WATER FROM ANY SWIMMING POOL, ARCHITECTURAL POOL OR SPA INTO ANY PUBLIC STREET, ALLEYWAY OR RIGHTS-OF-WAY.
REFILL / BILLING: each year in May, Glendale recalculates your sewer charge based on actual water usage billed during January, February and March (assuming 90 percent of a single-family home’s winter water goes to sewer, 95 percent for other dwellings).
Glendale explicitly lists as a typical valid sewer appeal: ‘The filling of a new pool or the draining and refilling of an existing pool, which affected your January, February or March bills.’ Appeals are filed as a Sewer Appeal with Customer Service and are accepted for 90 DAYS AFTER THE MAY BILLING. DROUGHT: Glendale’s 2022 Drought Management Plan contains ZERO mentions of the words ‘pool’ or ‘spa’ – residential pool filling is not addressed or restricted anywhere in it.
Its Stage 3 would bring mandatory restrictions on outdoor water use generally, to be presented to City Council before declaration, but pools are not named. The plan does define WATER WASTE as city-supplied water discharging from any property onto a street, sidewalk, gutter, alley, public utility easement, right-of-way or parking area, where the flow travels at least 250 feet from the property or accumulates in an area of at least 200 square feet – a definition a careless pool drain could meet.
Rules change and enforcement varies — confirm with your water provider before draining or refilling. Nothing here is legal advice.
Worth a look next door
- Filling a pool in Mesa — Same state, different water: Mesa fills at about 290 mg/L against 229 here.
- Filling a pool in Bakersfield — The other end of the scale: Bakersfield gets about 2.8 pool volumes of top-off against 0.7 pool volumes here.
Source: City of Glendale 2023 Water Quality Report (CCR) (2023 report data), accessed 2026-08-11. Values are the utility’s published system-wide figures; your tap can vary by service zone and season.
Data page generated 2026-08-15. Part of the pool fill-water lookup.