Published October 28, 2026 by A Clean Pool USA
The water that fills your pool is your city or county's drinking water, so it sets the starting point for your pool chemistry. Every utility in this guide says its supply is groundwater from the Floridan aquifer, and groundwater picks up dissolved minerals as it moves through rock. The main ones are calcium and magnesium, and together they make up what is called hardness.
Hardness is not the same everywhere. Where a utility publishes a figure, it runs from about 86 mg/L (Ocoee, converted from grains per gallon) to about 291 mg/L (the top of Deltona's range, also converted), which covers moderately hard to very hard on the USGS bands explained below. But 14 of the 21 utilities here publish no hardness figure that we could find, either in their water quality report or on their own water web pages. For those, this guide says "not published" and links the report we read. We did not fill the gaps with estimates or with third-party numbers.
Find your utility in the table below, then read its section. If you are not sure who supplies your address, your water bill will usually name your utility.
All 21 Utilities at a Glance
| Utility | Hardness | On the USGS bands (our reading) | Where the figure comes from |
|---|---|---|---|
| OUC | 129 mg/L | Hard | Utility web page, not the report |
| Orange County Utilities | Not published | No figure to rate | Not in the report |
| City of Apopka | 120 to 200 mg/L | Moderately hard to very hard | Water quality report |
| City of Winter Garden | Not published | No figure to rate | Not in the report |
| City of Ocoee | About 86 to 103 mg/L (converted) | Moderately hard | Water quality report |
| City of Oviedo | Not published | No figure to rate | Not in the report |
| City of Winter Park | Not published | No figure to rate | Not in the report |
| City of Maitland | 150 mg/L | Hard | Utility web page, not the report |
| Seminole County Utilities | Not published | No figure to rate | Not in the report |
| City of Lake Mary | Not published | No figure to rate | Not in the report |
| City of Longwood | Not published | No figure to rate | Not in the report |
| City of Winter Springs | 150 mg/L | Hard | Utility web page, not the report |
| City of Sanford | Not published | No figure to rate | Not in the report |
| City of Altamonte Springs | Not published | No figure to rate | Not in the report |
| City of Casselberry | Not published | No figure to rate | Not in the report |
| Toho Water Authority | Not published | No figure to rate | Not in the report |
| Volusia County Utilities | Not published | No figure to rate | Not in the report |
| Deltona Water | About 205 to 291 mg/L (converted) | Very hard | Utility web page, not the report |
| City of Clermont | Not published | No figure to rate | Not in the report |
| Polk County Utilities | About 115 mg/L (typical) | Moderately hard | Water quality report |
| City of Davenport | Not published | No figure to rate | Not in the report |
What the Numbers Mean
Hardness bands
Hardness is reported as milligrams per liter (mg/L) of calcium carbonate. For water, parts per million (ppm) means the same thing. A utility's hardness figure is total hardness, which counts magnesium as well as calcium, so the calcium hardness of the fill water is at most that figure. Some utilities print grains per gallon instead, and one grain per gallon is about 17.1 mg/L, which is the conversion this guide uses wherever it converts and says so. The USGS Water Science School gives these general guidelines for classifying water, as mg/L as calcium carbonate:
- 0 to 60 mg/L: soft
- 61 to 120 mg/L: moderately hard
- 121 to 180 mg/L: hard
- More than 180 mg/L: very hard
Utilities do not all grade water the same way. Maitland's FAQ calls 150 mg/L moderate on a 0 to 300 scale. Ocoee's report calls 5 to 12 grains per gallon moderate. Polk County Utilities calls water hard above 120 ppm. When a utility's own wording matters, its section quotes it. The "USGS bands" column in the table above is our reading of each published figure against the USGS bands, so every utility is graded on one yardstick.
pH and alkalinity
pH measures how acidic or basic the water is. Alkalinity is the water's buffer: how well it resists a change in pH. Only two utilities in this guide publish either number. Ocoee prints a pH of 7.8 to 7.9 and alkalinity of 79 to 103 ppm, and its own table calls a pH of 7 to 8 normal and 30 to 400 ppm good for alkalinity. Polk County Utilities' Northeast system prints an average pH of 8.0 and typical alkalinity of 130 ppm, and calls 60 to 120 ppm of alkalinity moderate. Everyone else prints neither.
What this means for your pool
For a plaster pool, a typical target for calcium hardness is roughly 200 to 400 mg/L. Your fill water sets the floor: a pool is topped off with it regularly, so the calcium in the fill water is where a fresh fill starts. Evaporation takes water out and leaves the calcium behind, so over a hot season the calcium in your pool creeps up. Rain pulls the other way for alkalinity. It is close to pure water, so a heavy storm dilutes alkalinity, which is one reason pH wanders after a storm.
Fill water that is high in pH and alkalinity pushes your pool's pH up. High pH makes chlorine work less efficiently and encourages scale on tile, plaster and the plates of a salt cell. Fill water that is high in calcium gets a pool to the top of its range sooner and leaves less room before scale becomes a risk.
Here is what the weekly visit does about each of those. We test the water, add acid to bring pH down or soda ash to bring it up, and check the salt cell for scale if your pool has one. The chemicals are included in weekly service.
Calcium works differently. When it climbs too high, the remedy is to replace some pool water with fresh fill water, and that only helps if the fill water has less calcium than the pool does, which is why the figure for your utility matters. Each visit ends with an emailed visit report that shows the calcium reading, so you know when dilution is due.
How we gathered the figures
Each figure comes from the utility's own water quality report (also called a Consumer Confidence Report) or, where the Source cell says "a utility web page, not the report", from a water page or FAQ on the utility's own website, checked on October 28, 2026. Third-party websites are never used. Where the utility prints no hardness, the table above says "not published" and the utility's section links the report we read. Conversions are marked as converted. Reports are updated every year and figures vary by well and by season, so check your utility's latest report before relying on a number.
Utility by Utility
OUC (Orlando Utilities Commission)
Serves: The City of Orlando (our Orlando page) and parts of unincorporated Orange County.
Water source: the Lower Floridan aquifer, treated at seven water-service plants.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 129 mg/L (printed as "129 ppm or 7 gpg", grains per gallon) | OUC water page (undated), checked 2026-10-28 (a utility web page, not the report) |
| pH | Not published | 2025 water quality report |
| Alkalinity | Not published | 2025 water quality report |
The 2025 report prints no hardness and no alkalinity. For pH it says only that finished water pH "remains within optimal range", with no number. OUC's water page prints the figure as "129 ppm or 7 gpg" and does not date it or state the basis (as calcium carbonate), so we show it exactly as printed.
Orange County Utilities
Serves: Orange County Utilities' 474-square-mile service area (Eastern, Southern and Western Regional systems plus seven small ones). The report names no cities and shows coverage only as a map.
Its water comes from the Floridan Aquifer, treated at four regional water facilities and eight remote facilities. The 2025 water quality report prints no hardness, pH or alkalinity. Some of its small systems buy water: Daetwyler Shores from OUC, and Magnolia Woods and Partlow Acres from the City of Winter Garden (see the OUC and Winter Garden sections). Ocoee's report says its Forest Lake Estates area is supplied by this utility's West Regional system.
City of Apopka
Serves: The City of Apopka's public water system. The report lists no neighborhoods.
Water source: the lower Floridan Aquifer, through thirteen wells at five treatment plants.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 120 to 200 mg/L (7.0 to 11.7 grains per gallon), as printed | 2025 water quality report |
| pH | Not published | 2025 water quality report |
| Alkalinity | Not published | 2025 water quality report |
The report's FAQ calls the city's water "moderately hard" and says to "contact the City to determine the actual hardness level in your area". It does not say which plant or area has which end of the range, so your address could be at either end of it, or between.
City of Winter Garden
Serves: The City of Winter Garden (our Winter Garden page). Per Orange County Utilities' report, the city also sells water to Magnolia Woods and Partlow Acres.
Its water comes from six deep wells drawing from the Floridan aquifer. The 2025 water quality report prints no hardness, pH or alkalinity.
City of Ocoee
Serves: The City of Ocoee (our Ocoee page). The report has two service areas: the primary area, served from Ocoee's own plants, and Forest Lake Estates, whose water comes from the West Regional system of Orange County Utilities.
Water source: Floridan Aquifer groundwater drawn from 340 to 1,450 feet down, aerated and chlorinated.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 5 to 6 grains per gallon as printed, about 86 to 103 mg/L (converted by us at 17.1 mg/L per grain) | 2025 water quality report |
| pH | 7.8 to 7.9 | 2025 water quality report |
| Alkalinity | 79 to 103 ppm, as printed | 2025 water quality report |
Caution on this row. The file's metadata title for the report ends in "DRAFT" (the visible pages do not say draft). The table these figures come from is an image inside the PDF, and it is not tied to one water system, so the report does not say whether it covers Forest Lake Estates, which gets Orange County water. Ocoee's report grades hardness in grains per gallon: under 5 soft, 5 to 12 moderate, over 12 hard.
City of Oviedo
Serves: The City of Oviedo's water system, which the city water page says serves approximately 40,000 residents and commercial establishments. Seminole County's report says its Black Hammock area buys Oviedo water (see the Seminole County Utilities section).
Its water comes from ten wells in the Floridan aquifer at the West Mitchell Hammock Water Treatment Facility. The 2024 water quality report prints no hardness, pH or alkalinity. It is the newest report Oviedo has posted on its site as of October 28, 2026.
City of Winter Park
Serves: The City of Winter Park's water system (about 23,000 connections per the report).
Its water comes from six wells in the lower Floridan aquifer, up to 1,330 feet deep. The 2025 water quality report prints no hardness, pH or alkalinity.
City of Maitland
Serves: The City of Maitland's water system (over 5,800 water meters per the report). The report does not itemize areas.
Water source: six wells in the Floridan Aquifer feeding three potable water plants.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 150 mg/L, as printed | Maitland water FAQ (undated), checked 2026-10-28 (a utility web page, not the report) |
| pH | Not published | 2025 water quality report (a large file, about 84 MB) |
| Alkalinity | Not published | 2025 water quality report (a large file, about 84 MB) |
The FAQ rates 150 mg/L as "moderate" on its own 0 to 300 scale, where moderate runs 75 to 150. On the USGS bands above, 150 mg/L is hard. The FAQ gives no date, sampling date or location. The 2025 report's results table is an image and has no hardness, pH or alkalinity line.
Seminole County Utilities
Serves: Unincorporated Seminole County, in 11 service areas. This section covers the four areas whose water the county supplies itself: Northeast, Northwest, Southeast and Southwest. The report names no cities for them. The other seven areas buy their water from a neighboring utility, so use that utility's section for them:
- Apple Valley and Druid Hills: City of Altamonte Springs
- Black Hammock: City of Oviedo
- Chase Groves: City of Sanford
- Sun Shadows: City of Casselberry
- Lake Brantley and Meredith Manor: Sunshine Water Services (Sanlando Utilities). It has no section in this guide, so read its own report.
Its water comes from groundwater wells in the Floridan Aquifer, treated differently in each area (aeration, ozone, ion exchange or carbon filtering, then disinfection). The 2025 water quality report prints no hardness, pH or alkalinity. The Northwest section says that water is treated with ion exchange but makes no hardness statement. The report has no table of suppliers; we matched each area to its supplier from the "from whom we purchase your drinking water" paragraph in that area's section.
City of Lake Mary
Serves: The City of Lake Mary's water system. The report states no service area and notes four water main interconnections with Seminole County and one with Sanford.
Its water comes from six groundwater wells in the upper Floridan Aquifer, feeding one treatment plant (the city's Potable Water page says five wells; we use the report's six). The 2025 water quality report (a web page) prints no hardness, pH or alkalinity.
City of Longwood
Serves: The City of Longwood's water system; the report states no service area.
Its water comes from five wells in the Floridan aquifer, 300 to 500 feet deep, aerated and then disinfected. The 2025 water quality report prints no hardness, pH or alkalinity.
City of Winter Springs
Serves: The City of Winter Springs (about 14,215 connections per the report). Dovera has its own annual report on the city's site and is not covered here.
Water source: eight groundwater wells in the Floridan aquifer supplying three treatment plants.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 150 mg/L ("or 8 grains" per gallon), as printed | Winter Springs potable water page (undated), checked 2026-10-28 (a utility web page, not the report) |
| pH | Not published | 2025 water quality report |
| Alkalinity | Not published | 2025 water quality report |
The 2025 report itself prints no hardness, pH or alkalinity. Its treatment section mentions ion exchange at one plant, but says that is to reduce total organic carbon.
City of Sanford
Serves: The City of Sanford (our Sanford page) and unincorporated portions of Seminole County, per the city water and sewer page. Seminole County's report says its Chase Groves area buys Sanford water.
Its water comes from seventeen groundwater wells in the Floridan Aquifer (thirteen at the Main Water Plant, four at the Auxiliary Water Plant). The 2026 water quality report (2025 data) prints no hardness, pH or alkalinity.
City of Altamonte Springs
Serves: The City of Altamonte Springs (our Altamonte Springs page). Seminole County's report says its Apple Valley and Druid Hills areas buy Altamonte Springs water.
Its water comes from the city's six wells in the Floridan aquifer, with tray aeration and chlorination. The 2025 water quality report prints no hardness, pH or alkalinity.
City of Casselberry
Serves: The City of Casselberry (our Casselberry page) and areas outside the city limits; the city utilities page says it serves over 50,000 people in all. Seminole County's report says its Sun Shadows area buys Casselberry water.
Its water comes from wells in the Floridan Aquifer at three treatment facilities (North Plant, South Plant and Howell Park). The 2025 water quality report prints no hardness, pH or alkalinity.
Volusia County Utilities
Serves: The county's VC/Southwest Interconnect water system, the report we match to the DeBary area. The report itself names no cities, and we found no current county page that ties a report to DeBary addresses. The only county page we found that names a DeBary service area is an older rate page (it mentions 2012 and 2013 rate changes). It lists DeBary among the county's unsoftened west Volusia areas and an area called Glen Abbey in DeBary, which is also the name of this system's main plant. Confirm your address with Volusia County Utilities.
Its water comes from seven wells in the Floridan Aquifer feeding four treatment plants; the water is disinfected with chloramines (chlorine plus ammonia). The 2025 water quality report prints no hardness, pH or alkalinity. The report says the county monitors its wells and plant output to keep "pH, alkalinity, and calcium levels" optimal, but it prints no values for them.
Deltona Water
Serves: The City of Deltona. The report adds that Deltona Water also serves Stone Island and Enterprise, and supplies other county locations through interconnects as needed.
Water source: groundwater from the Floridan aquifer, treated with aeration, chloramines and a phosphate-based corrosion control chemical.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 12 to 17 grains per gallon as printed, about 205 to 291 mg/L (converted by us at 17.1 mg/L per grain) | Deltona Water FAQ (undated), checked 2026-10-28 (a utility web page, not the report) |
| pH | Not published | 2025 water quality report |
| Alkalinity | Not published | 2025 water quality report |
The FAQ says the spread comes from different wells having different hardness around the city. The 2025 report itself prints no hardness, pH or alkalinity.
City of Clermont
Serves: The City of Clermont; the one report covers two water systems, East and West, divided by US Highway 27.
Its water comes from eight wells in the Floridan Aquifer, with minimal chlorine disinfection. The 2025 water quality report prints no hardness, pH or alkalinity. Its results table is an image.
Polk County Utilities
Serves: Unincorporated north-east Polk County, including Davenport mailing addresses outside the city limits, through the Northeast Public Water System (the Northeast Regional Utility Service Area of Polk County). The report names no cities; the county's water conservation policy manual lists a Polo Davenport plant among the Northeast system's plants (a plant list as of 2018). Homes inside the City of Davenport are on the city's own system: see the City of Davenport section. Champions Gate: utility not confirmed. No utility document we read names it.
Water source: 18 wells in the Floridan aquifer plus water bought from Toho Water Authority, at six treatment facilities.
| Measure | Published value | Source |
|---|---|---|
| Hardness | 115 mg/L (printed as "typically around 115 ppm, or 6.7 grains per gallon") | 2025 Northeast water quality report |
| pH | Average 8.0 | 2025 Northeast water quality report |
| Alkalinity | Typically around 130 ppm, as printed | 2025 Northeast water quality report |
This is the only report in the guide that prints all three numbers, and they are "typically around" and "average" values for the whole Northeast system, not ranges. The system also receives purchased Toho water, and Toho publishes no hardness, so figures at a given address may differ. The report defines hard water as more than 120 ppm (7 grains per gallon), so 115 ppm sits just under its own line.
City of Davenport
Serves: The City of Davenport's own public water system (PWS FL6530431), for homes inside the city. Davenport mailing addresses outside the city limits are covered in the Polk County Utilities section.
Its water comes from three wells in the Upper Floridan Aquifer; the water is aerated, then disinfected with chlorine. The 2025 water quality report prints no hardness, pH or alkalinity. Its only scale-related text is a general tip that white scaling on faucets and showerheads may be caused by high levels of calcium carbonate, with no number.
Let Us Handle the Chemistry
A Clean Pool USA provides weekly pool service with chemicals included. Each visit ends with an emailed visit report with readings, chemicals added and photos.