24/7 Emergency Service

Mineral Buildup in Solar Water Heaters

THE DOCTOR IS IN! Deer Valley Plumbing is here to ensure that your solar water heaters are working at optimum condition. Solar water heaters, like all other appliances, are susceptible to wear and tear over time, but this can speed up with high mineral buildup. This mineral buildup typically consists of magnesium and calcium which look like white particles or tiny pieces of paper. While there is no ‘apple a day’ sure-fire cure, regular maintenance and checkups can help you keep your solar energy systems in check.

What problems should I look for in my solar water heater?

Collector Shading & Debris

First, just take a look at your solar water heater. This annual check should be done during the day to see whether any new construction in the house, changes in neighbors’ property, or vegetation growth is causing shading which wasn’t there at the time of installation. Shade changes the efficiency of your solar water heater (for obvious reasons). Also, make sure to clean out any debris and dust that builds up on the unit every couple of months.

Collector Glazing and Seals

Glazing and seals are indicative of the condition of your solar panel. Any cracks in the collector may require immediate attention. Also check the glaze of your solar water heater for discoloring. If the glazing is becoming yellow, it may have to be changed.

Wiring, Ductwork and Piping

Make sure that there are no fluid leaks in the pipe connectors and that the ducats are sealed with mastic compound. All wired connections, insulation, and duct piping should be tight.

What do I do if I find mineral buildup in the solar water heater?

Heat transfer fluids

All this talk about heaters, but you can’t forget to stay cool. Antifreeze liquid solutions within solar water heaters need to be replaced at regular intervals. When hard water circulates in the collectors, the mineral buildup may cause obstructions within the piping systems. In this case, a mild acidic solution or a descaling solution may have to be added to the water. This is where we step in. These solutions prevent a lot of hard water mineral buildup, however their addition should be handled by professionals as they are highly toxic.


Draining or flushing the water heater helps get rid of any calcium and magnesium deposits floating in the water. This cleanup needs to be done every 6 months to ensure that the heater is working at optimal condition. In order to effectively flush out the water heater, turn off the energy supply and close the water supply valve to ensure no more water is flowing into the tank. There should be another valve at the bottom of the tank specifically for the purpose of draining it out. Connect a hose to that valve and allow it to drain into a safe location. Make sure to prevent contact with the water since it might be quite hot.


Heat is also a contributing factor for mineral buildup. The hotter the water is, the more calcium and magnesium will be derived from the solution, creating solid deposits in the heater. A high thermostat can magnify the problem. To prevent mineral buildup, keep the temperature at about 120 degrees Fahrenheit.

Installing a water softener system can seriously help reduce the mineral buildup in solar water heaters! This system is designed to get rid of the ions, calcium, and magnesium dissolved in the water that make it hard. Check out our page on water softeners to learn more about how to take care of your plumbing system.