Short answer
Cleveland Water reported average hardness of 117 mg/L as calcium carbonate in 2025, with a range of 105 to 130. That is about 6.8 grains per gallon, at the top of the USGS moderately hard band. It is enough to build sediment in a tank and scale in a tankless unit over time, but it is not unusually hard water.
Key facts
- Cleveland Water's 2025 water quality report lists hardness as calcium carbonate at an average of 117 mg/L, with a range of 105 to 130 mg/L.[1]
- Cleveland Water describes its water as about 7 grains per gallon, or 120 mg/L as calcium carbonate.[2]
- Akron's 2025 water quality report lists hardness at 107 mg/L, or 6 grains per gallon, with a range of 76 to 150 mg/L.[3]
- Rinnai recommends a yearly flush for residential tankless units in water from 61 to 160 mg/L (4 to 9 grains per gallon).[7]
How hard is the water in Cleveland?
Cleveland Water's 2025 water quality report puts hardness at an average of 117 mg/L as calcium carbonate, with a range of 105 to 130 mg/L[1]. Divide by 17.1 and that is about 6.8 grains per gallon (our conversion). Cleveland Water's own plain-language article rounds it to "7 grains/gallon or 120 mg/L"[2].
On the USGS scale, 61 to 120 mg/L is moderately hard and 121 to 180 mg/L is hard[5]. Cleveland's average sits at the top of the moderately hard band, and the high end of its range crosses into hard.
One detail for careful readers: the same 2025 report also lists calcium at 16 mg/L and magnesium at 7.6 mg/L, which would compute to a lower hardness[1]. We report the printed hardness line, because that is the figure the utility publishes for hardness.
Which suburbs get the same water?
Cleveland Water supplies a large share of Cuyahoga County. Lakewood, for example, runs its own pipes but buys its water from Cleveland Water[8]. Other systems in the metro publish their own numbers:
| Water system | Hardness (as CaCO3) | Grains per gallon | Source |
|---|---|---|---|
| Cleveland Water (Cleveland, Lakewood, Parma, Euclid, Strongsville, Cleveland Heights) | Average 117 mg/L, range 105 to 130 (2025) | About 6.8 | [1] |
| Akron Water Supply Bureau | 107 mg/L, range 76 to 150 (2025) | 6, range 4 to 9 | [3] |
| Cuyahoga Falls Water Department | Finished hardness 100 to 130 mg/L (2025 target, partly softened at the plant) | About 6 to 8 | [4] |
| Aqua Ohio (Mentor) | Not published in the sources we read | n/a | [9] |
| Lorain and Elyria | No hardness figure in the 2025 reports we read | n/a | n/a |
If your figure is missing, call the utility named on your bill and ask for the hardness in mg/L or grains per gallon.
What does this water do to a tank water heater?
Hardness minerals settle out when water is heated. In a tank they collect on the bottom as sediment. The usual signs are popping or rumbling as the burner heats water trapped under the scale, and slower recovery. See popping and rumbling noises.
At Cleveland's level, sediment builds slowly rather than fast. A tank that is flushed on the maker's schedule should reach a normal service life. Rheem puts tank water heaters at 8 to 12 years and tankless units at 15 to 20 years or more with proper care[6]. Many web pages quote 10 to 15 years for tanks; that is longer than the manufacturer figure.
Practical steps for a tank in Cleveland water:
- Drain and flush the tank as the owner's manual directs. Many manuals call for about once a year.
- Have the anode rod checked when the tank is a few years old. It is the part that wears out so the tank does not.
- Note the install date on the tank. Use our age decoder if you do not know it.
What about tankless units?
Tankless heaters are more sensitive to scale, because the water passes through a small heat exchanger. Rinnai's SENSEI manual sorts water from 61 to 160 mg/L (4 to 9 grains per gallon) into one band and recommends a yearly flush for residential units in it, plus a softener or scale control system[7]. Cleveland, Akron and Cuyahoga Falls water all fall in that band[1][3][4].
Rinnai also notes that scale builds faster at higher temperature settings[7]. Scale warnings show up as codes, such as LC on Rinnai units. See how to descale a tankless water heater.
Myth check: "Cleveland has very hard water"
Softener ads sometimes describe Northeast Ohio water as "very hard." On the USGS scale, very hard starts above 180 mg/L[5]. Cleveland Water's 2025 range tops out at 130[1]. Some Ohio cities do have much harder water; see water hardness by city. Cleveland is not one of them.
That does not make maintenance optional. It means a flush schedule, not a whole-house system, is the baseline for protecting a water heater here. If a salesperson tests your water, ask for the number in mg/L and compare it with your utility's report.
When to call a pro
- A tank that pops loudly, leaks at the base, or runs out of hot water much faster than it used to.
- A tankless unit showing a scale or service code you cannot clear after a flush.
- A drain valve that will not close after flushing, or a tank too old to flush safely (sediment can clog the valve).
- Any gas tank showing rust or soot at the burner area or the vent.
More questions
Do I need a water softener in Cleveland?
Not to protect a water heater in most cases. Cleveland Water sits near the line between moderately hard and hard. Regular tank flushing and, for tankless, yearly descaling handle it. A softener is a comfort choice for spotting and soap use. Rinnai recommends softening or scale control for tankless units in this range, so read your own maker's manual.
Is suburban water the same as Cleveland's?
Many suburbs buy from Cleveland Water, including Lakewood, Parma, Euclid and Strongsville, so their figure is the same. Akron, Cuyahoga Falls and Mentor have their own suppliers. Check the name on your water bill and read that utility's annual report.
Sources
- 2025 Water Quality Report, Cleveland Water (City of Cleveland Division of Water). Accessed 2026-10-07.
- What is hard water, and should you worry about it? (Mar 9, 2022), Cleveland Water. Accessed 2026-10-06.
- 2025 Water Quality Report, City of Akron Water Supply Bureau. Accessed 2026-10-07.
- 2025 Consumer Confidence Report, City of Cuyahoga Falls Water Department. Accessed 2026-10-07.
- Hardness of Water, U.S. Geological Survey, Water Science School. Accessed 2026-10-07.
- Water heater lifespan: when to repair vs. replace (Mar 25, 2026), Rheem Manufacturing. Accessed 2026-10-06.
- SENSEI RX Residential Installation and Operation Manual (100000839), Rinnai America. Accessed 2026-10-06.
- Water and Wastewater Collection, City of Lakewood, Ohio. Accessed 2026-10-06.
- Utilities and other local links, City of Mentor. Accessed 2026-10-06.
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