We have a house at the lake, and we use water from a well. The problem is that our toilet tank sweats. I am trying to catch the moisture by laying towels underneath the tank. Is there anything we can do? Do we need to replace the toilet? We need your advice. Thank you

Thanks for your letter. Don't you hate it when a toilet takes on a personality of its own? You may have a moody toilet—it's sweating to let you know it's alive.

All kidding aside, there are few things that may be causing the tank to sweat. My first guess is that water is running or leaking within the fill tank. You can diagnose this by the annoying noise, increased water usage, and cold tank water. When the water continues to run, it never gets a chance to reach room temperature. Basically, the cold tank reacts to the warm moist room temperature (especially after someone takes a shower) causing condensation (sweating) to occur on the outside of the tank.

A quick and easy way to diagnose a leak is to add some food coloring to the tank and check back later to see if the color has migrated to the bowl water.

What causes the water to continue to run? It could be several things: the float arm doesn't rise high enough, the float ball becomes water-logged, or either a tank ball or flapper (stopper) does not seat correctly in the valve seat. It's also possible that water is leaking from the ballcock's diaphragm or the float ball rises too high which causes water to flow into the overflow tube. In your case, it's possible that your well water is extremely cold.

First, identify if you do indeed have a leak or running water. Check the valve seat for corrosion or foreign material that prevents the stopper from seating properly. If the stopper is soft or cracked, replace it. If there's a high concentration of chlorine or chlorine-related products in the water supply (unlikely here since you are using well water), install a stopper designed for use in harsh water conditions. Check for a broken link between the handle and trip lever and if the tank stopper closes before the tank has a chance to empty. Check that the float ball rises to the proper height. Water should remain at least 1 inch below the overflow tube. Check for cracks in the overflow tube. It's possible that the ballcock is worn out and needs replacing. You can find the ballcock where the water supply attaches to the ballock tailpiece on the left-hand side on the bottom side of the tank or where the float arm attaches to the ballcock within the tank.

If you have corrected all this and you still have condensation, there are a few other steps to take. If the condensation occurs after a shower, try not to flush the toilet until all moisture has left the room. Accomplish this by turning on your exhaust fan 15 minutes prior to a shower and leaving it on for at least 20 minutes afterward. Also, leave the door partway open when taking a shower. If you don't already have a fan, I suggest that you install one. It also helps if you dry down the shower walls after showering using a squeegee and a chamois. You could also insulate the tank with an expanded polystyrene liner. Check with your local home center for a toilet tank-liner or insulation kit. If they don't have them, check out the ThermoSafe toilet tank-liner at www.plumbingproducts.com.

You could install a new toilet with a factory-installed liner or a 1.6 gpf toilet. Low-flow toilets are less likely to sweat as they only use part of the water in the tank and usually warm up before the next flush. In your case, if the well water is extremely cold, consider using a fishtank heater in the fill tank to warm the water a bit. I also recommend that you not use an automatic toilet bowl cleaner in the tank—most contain chlorine, which can adversely affect the internal parts in the tank as well as the liner. If your home has a lot of humidity, install a dehumidifier.

As an absolute last resort, you could install a thermostatic mixing valve for sanitary systems. These valves mix hot and cold water supplies to deliver water at a controlled temperature. The temperature is controlled by constant monitoring of the outlet temperature by a thermostatic element which adjusts the mix ratio of hot and cold water according to the manual temperature setting of the valve. However, in order to install this system, you will have to plumb in the hot water. Your hot water energy expenses may also increase.

Before replacing any tank component parts in the fill tank, turn off the water at the toilet shutoff valve. Empty the tank by flushing the toilet and soak up any remaining water using a sponge.

I've given you a lot to consider. Just take it one step a time and let me know which solution (or combination of solutions) works.

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C.R.S., Inc. · Spokane, Washington · USA