Fountain Valley water hardness, explained

The City supplies water from six City wells and one imported water connection. In a normal year, the City's FAQ says the mix is about 85% local groundwater from the Orange County Groundwater Basin and about 15% imported water from the Metropolitan Water District of Southern California (MWD), which draws on the Colorado River and the State Water Project. The 2026 report says that in 2025 the City provided only groundwater.

That matters for hardness. The City FAQ describes imported water from the Colorado River and Northern California as moderately hard, and the City's well water as hard. So a year with no imported water is a year at the harder end of what Fountain Valley taps see. The FAQ also notes that the mix varies through the year, which can change both taste and hardness. If your water seemed different from one season to the next, that is a likely reason.

Disinfection differs by source too. The City adds chlorine to well water as it enters the distribution system. MWD treats its imported water with chloramines, a mix of chlorine and ammonia. In a year like 2025, Fountain Valley homes were on chlorinated well water.

The GWRS is a joint project of OCWD and the Orange County Sanitation District (OC San). It sits in Fountain Valley next to OC San's Plant No. 1, which supplies it with treated wastewater. OC San describes it as the world's largest advanced water purification system for potable reuse.

The original plant opened in 2008 and produced up to 70 million gallons a day. By late 2022 it was producing 100 million gallons a day, and it was designed for a final capacity of 130 million gallons a day, enough for about 1 million people. The City's 2026 report says the GWRS can produce up to 130 million gallons per day and supplies about 35 percent of the water that refills the basin each year. It also says the system reduces dependence on imported water from the Sacramento to San Joaquin River Delta and the Colorado River.

For a Fountain Valley homeowner, the takeaway is simple. The water in your pipes is local, it is managed carefully, and it meets drinking water standards. It is also hard, because it is groundwater. The GWRS is part of why the region can lean so heavily on its own basin.

A note on white bits in your faucet screens

Not every white flake is scale. The City FAQ explains that some water heater brands used dip tubes that break down over time. The white plastic pieces can clog faucet strainers and showerheads. A simple test: those pieces only show up in hot water, so the toilet tank and ice maker should be clear. If the flakes are only on the hot side, the City suggests contacting the heater's manufacturer. Scale, by contrast, tends to show up on both hot and cold fixtures and gets worse where water is heated.

Hot water temperature

Scale forms faster at higher temperatures, so it is tempting to turn the heater way down. The City FAQ cautions against setting a water heater below 130 degrees Fahrenheit, to prevent bacterial growth, and asks for care with scalding in homes with young children or elderly or disabled residents. If you are unsure where to set yours, ask your plumber to check it during service.

Many Fountain Valley homes pair a whole-house softener with a drinking water filter at the kitchen sink. Others choose a conditioner and accept some scale in exchange for less upkeep. Sizing, salt use, brine discharge rules and installation are covered in depth on our water softeners and filtration page, so we keep this guide to the numbers and the basics.

If you only want to protect one appliance, there are smaller steps. Flushing a tank heater once a year, as the City recommends, and descaling a tankless unit on the manufacturer's schedule both help. So does cleaning aerators and showerheads in a vinegar soak a few times a year.

Most of Fountain Valley was built in the 1960s and 1970s, under the master plan the City's history describes. Typical slab homes of that era in Orange County had copper supply lines in or under the slab and a gas water heater in the garage. Many of those homes have had several water heaters by now. Some still have original angle stops and shutoffs that have not been turned in years.

Here is what we look for on a service call in a home that has been on hard water a long time:

• Sediment noise and slow recovery from a tank water heater
• Crusty buildup at the water heater's connections and relief valve
• Main and fixture shutoff valves that will not close fully
• Reduced flow at showers, often a scaled showerhead or cartridge
• Toilets that run, often a scaled fill valve or flapper seat
• Tankless units throwing error codes or swinging in temperature

None of this means a house needs major work. Most of it is routine maintenance that hard water speeds up. Across Central, North and West Fountain Valley, and in the tracts around Mile Square Park, the water is the same City water, so the patterns are the same too.

If a leak, a dead water heater or a failed valve turns urgent, our 24/7 emergency plumber line answers day and night at (657) 669-4766. You get a written price before work starts, and the work is done by independent CSLB-licensed C-36 plumbing contractors.