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Sediment in Water

With more and more residents installing tankless water heaters and filters, Roxborough WSD has started to receive more frequent complaints of sediment in the water. I thought I would share my personal experience.

Two years ago my husband and I had a new whole-house humidifier installed. A whole-house humidifier works similarly to a whole-house filter except that it heats the water. We selected a state-of-the-art unit that cost $2,000. The manufacturer’s recommended maintenance included replacing the filter on the unit annually. Like a lot of people, we completely forgot to change the filter for about 18 months when the humidifier stopped working. We had it checked and, not surprisingly, it needed a new filter, and that replacement filters cost $100 each. When we installed the new filter, we had to literally dig out light brown sandy material from the unit. We cleaned out the accumulated material and installed the new filter. Six weeks later we replaced the filter again because the humidifier controller indicated it needed to be replaced. By the way, we don’t live in Roxborough; we live in an area served by Denver Water. However, Roxborough WSD and Denver Water have the same source water – the South Platte River. That water supply is clean, mountain snow melt that we are blessed to have, but it is a hard water source.

Hardness is most commonly expressed as milligrams of calcium carbonate equivalent per liter. Water containing calcium carbonate at concentrations below 60 mg/l is generally considered as soft; 60–120 mg/l, moderately hard; 120–180 mg/l, hard; and more than 180 mg/l, very hard (McGowan, 2000).

Roxborough WSD’s source water is high mountain surface water, so it is expected to be moderately hard. Total hardness measured as CaCO3 is typically between 90-100 mg/L or parts per million (ppm). There is no Safe Drinking Water Act standard for hardness. The World Health Organization recommends a limit of 75 mg/L for calcium, but there is no Safe Drinking Water Act standard. Recent sampling of Roxborough’s water showed total hardness of 96.8 mg/L as CaCO3, and calcium of 25.9 mg/L.

That calcium carbonate, calcium, and traces of iron and manganese in the water are captured by filters or form scale in the tankless water heaters. If the filters and water heaters aren’t cleaned or changed regularly, the residue will be released and look like sediment in the water. The manufacturer’s recommended maintenance is based on operation in parts of the country with much softer water. Also, quite frankly, no one who is selling you an expensive home filter or tankless water heater is going to go out of their way to tell you that your expensive new unit is going to need $100 replacement filters every 6-8 weeks rather than once a year.

Roxborough WSD takes every complaint of sediment or discolored water very seriously. When we receive a complaint, we send crews out to flush the main near the home as soon as possible, and the water typically runs crystal clear.

So please if you have a home filter, change your filter frequently. Probably more frequently than the manufacturer recommends. If you have a tankless water heater, here’s a link to a video on flushing your water heater The manufacturer probably recommends you flush the water heater every 6-8 months but based on my personal experience, I’d suggest you think about flushing it monthly.

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