How Los Angeles Hard Water Destroys Water Heaters (And How to Prevent It)

June 2, 2026  |  Maintenance

If you live in Los Angeles, you've probably noticed the white crusty deposits around your faucets, showerheads, and sink drains. That's calcium and magnesium — the minerals that make LA water among the hardest in the United States. And while scale on your faucet is annoying, what it's doing inside your water heater is far more serious.

How Hard is LA Water?

Los Angeles tap water comes from two main sources: the Metropolitan Water District (imported from the Colorado River and Northern California) and local LADWP groundwater. Both sources are high in dissolved minerals.

The hardness of LA water typically ranges from 200 to 400 milligrams per liter (12 to 23 grains per gallon), depending on your neighborhood and the current source blend. For reference:

• Soft water: below 60 mg/L
• Moderately hard: 60–120 mg/L
• Hard: 120–180 mg/L
• Very hard: above 180 mg/L — this is Los Angeles

What Hard Water Does to a Tank Water Heater

Every gallon of water that flows into your tank deposits a tiny amount of mineral scale. Over months and years, this scale accumulates on the floor of the tank and around the heating elements. The effects are progressive:

• Year 1–2: Minor scale, negligible impact on efficiency
• Year 2–4: Scale layer thickens. You may hear popping or rumbling sounds — water boiling beneath the scale crust. Energy consumption increases 5–10%.
• Year 4–7: Significant scale. Tank floor overheats. The glass lining begins to crack. Water has a slightly metallic taste.
• Year 7+: Tank lining has failed. Rust begins. Unit needs replacement.

A well-maintained tank water heater in LA should last 10–14 years. An unmaintained one in hard water commonly fails at 6–8 years — costing you thousands in premature replacement.

What Hard Water Does to a Tankless Water Heater

Tankless water heaters are even more vulnerable to hard water than tank units. Because the water is heated instantaneously through a narrow heat exchanger, the flow rates and temperatures involved accelerate scale formation dramatically.

Scale in a tankless heat exchanger:

• Reduces flow rate, causing activation problems and error codes
• Reduces heat transfer efficiency, causing overheating and thermal shutdowns
• Can permanently crack the heat exchanger — the most expensive component in the unit

The most common error codes triggered by scale in LA — Navien 27, Rinnai LC, Noritz 59 — are essentially your water heater asking to be descaled.

The Solution: Annual Maintenance

The good news is that hard water damage is almost entirely preventable with annual maintenance:

• Tank water heaters: Annual flushing removes sediment before it hardens. Takes about 30–45 minutes.
• Tankless water heaters: Annual descaling (flushing with a food-grade descaling solution) dissolves scale deposits in the heat exchanger. Takes about 1–2 hours.
• Water softener: Installing a whole-house water softener is the most comprehensive solution — it removes hardness minerals before they enter any appliance, dramatically extending the life of your water heater, dishwasher, washing machine, and plumbing.

Simple Water Heater & Filtration offers annual maintenance service for both tank and tankless water heaters throughout Los Angeles and the San Fernando Valley. Contact us to schedule a maintenance visit.