Toilet tank sweats a lot in summer time. What can I do myself?

1) Insulate inner toilet tank. They sell kits for this, but they are hard to find. You could also purchase some rigid foam insulation and some good quality adhesive and make your own kit.

2) Install an antisweat valve where you pipe hot water and cold water to a mixing valve and feed warm water to the toilet tank:

B and K Industries 109-503RP Anti-Sweat Toilet Tank Valve - Amazon.com (http://www.amazon.com/Industries-109-503RP-Anti-Sweat-Toilet-Valve/dp/B000BQMKCY/ref=sr_1_1?ie=UTF8&qid=1391529116&sr=8-1&keywords=toilet+anti+sweat)

Questions? Let me know, OK?

Mark

Mark gave you some solutions ./ here are a few more.Click on Amazon and then toilet tank covers, (see image). You could also install a dehumidifier or increase the air flow from your AC. Good luck, Tom