In the southwest US, calcium carbonate concentrations in potable water tend to be higher than the national average. With the addition of CAP water into many of the municipal drinking water supplies, the levels are going even higher. When water is heated and cooled, the dissolved calcium carbonate can precipitate or fall out. Traditional water heater manufacturer’s recommend flushing the particulates or solids from the bottom of the tank. Solar hot water systems are also affected by high calcium levels but the overall affect of the equipment varies.

An active solar hot water system uses the back-up heat infrequently. The solar heating portion doesn’t cause the calcium to precipitate; therefore the solid build up tends to be less. Solar tank manufacturer’s still recommend flushing the tank to remove the solids.

For a passive system, we have seen little to no affect of calcium on the collector. The back-up traditional tank or tankless water heater will require the manufacturer’s recommended service.

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