Hard water in Aliso Viejo, CA

Tap water hardness
160mg/L
9.3gpg
Hard

Reported by Moulton Niguel Water District · September 2025

CA typical
121 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

The water in Aliso Viejo carries roughly 160 mg/L of dissolved calcium and magnesium, or 9.3 grains per gallon. That is hard water. The number comes from Moulton Niguel Water District, dated September 2025.

Aliso Viejo on the hardness scale, with nearby cities
060120180240300360+CA typical 121Laguna Beach: 98 mg/LLaguna Beach 98Irvine: 98 mg/LIrvine 98Laguna Woods: 108 mg/LLaguna Woods 108Laguna Niguel: 151 mg/LLaguna Niguel 151Ladera Ranch: 158 mg/LLadera Ranch 158Las Flores: 158 mg/LLas Flores 158San Juan Capistrano: 158 mg/LSan Juan Capistrano 158Coto de Caza: 158 mg/LCoto de Caza 158Mission Viejo: 159 mg/LMission Viejo 159Laguna Hills: 160 mg/LLaguna Hills 160Aliso Viejo 160mg/L as calcium carbonate060120180240300360+CA 121Laguna Beach: 98 mg/LLaguna Bea. 98Laguna Woods: 108 mg/LLaguna Woo. 108Laguna Niguel: 151 mg/LLaguna Nig. 151Ladera Ranch: 158 mg/LLadera Ran. 158Mission Viejo: 159 mg/LMission Vi. 159Laguna Hills: 160 mg/LLaguna Hil. 160160 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Aliso Viejo sits 39 mg/L above the typical California figure of 121. None of the 10 nearest cities we track has harder water. The range nearby runs from 98 mg/L in Laguna Beach to 160 in Laguna Hills.

What 160 mg/L means at home

Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.

Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.

Soap and detergent need a little more to lather, and soap scum shows up in the tub.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

At 160 mg/L most of the trouble is scale, and only a few things deal with it.

Ion-exchange water softener

The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.

Salt-free conditioner

No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.

Reverse osmosis or carbon filter

Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.

Softener size for Aliso Viejo

3 people × 75 gallons a day × 9.3 gpg = 2,102 grains a day. A 24,000-grain unit regenerates about every 11 days.

Size it for your household

EPA record for Aliso Viejo's water system

Moulton Niguel Water District · PWSID CA3010073

No health-based violations since 2016

Serves about 168,315 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

TapWaterData ties Aliso Viejo to this system. EPA's service-area records do not name Aliso Viejo, so check the utility printed on your water bill.

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Aliso Viejo water hard?

Yes. It measures about 160 mg/L (9.3 grains per gallon), which the USGS classes as hard.

What is the water hardness in Aliso Viejo in grains per gallon?

About 9.3 gpg. One grain per gallon equals 17.1 mg/L, so 160 mg/L divided by 17.1 gives 9.3.

What size water softener do I need in Aliso Viejo?

For 3 people using 75 gallons each per day, 9.3 gpg works out to about 2,102 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.

Has the Aliso Viejo water system had EPA violations?

EPA records show no health-based violations for Moulton Niguel Water District since 2016.

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, September 29, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.