My incoming water pipe is copper and it is a brand new installation with no leaks. But due to the hot humid weather (even in the basement) it sweats due to condensation. Should I insulate it?
The problem is last year I insulated some copper pipes only to find a year later that they all corroded due to the water trapped between the pipe and the insulation.
I wouldn't bother insulating your incoming cold water pipes. If your basement is warm, the water will warm up a little passing through it, but the solution to that -- if you need it -- is to let the cold water run for a little until you're see water that hasn't been sitting around in your pipes getting warm. I say "if you need it" because I generally don't care what temperature my cold water is: drinking water for me comes from a pitcher in my fridge; tap water is used for washing food, mixing with hot water for bathing, or watering plants.
If you're concerned about the condensation from your pipes dripping onto things, I'd be more inclined to get a dehumidifier and run it while you've got this hot, humid weather.
The only reason to insulate your incoming water feed is if there is a risk of it freezing during the winter, in which case it's essential.
If it's properly insulated - i.e. there's no gaps in the insulation and there's no gap between the insulation and the pipe then you shouldn't have a problem with condensation as there'll be no way the warm moist air can get to the cold pipe.
Copper pipes should be properly insulated. It will not cause the pipe to corrode. To insulate properly the insulation needs to be sealed properly to avoid warm moist air reaching the pipes and condensing and then dripping. Seal the seams, where it joins to the next section and where it passes through the bulkhead into the space. Also try to reduce the humidity of the space. In cold climates we have to insulate our copper pipes to prevent frost damage and never seen corrosion in 50 years caused by insulation. Plenty of damage though caused by frost.
Although counter intuitive, DO NOT INSULATE copper pipes...hot or cold. It will result in corrosion. When the hot water is not being used (at night for instance when everyone is asleep) the copper hot water supply pipes are the same temperature as the cold water pipes. If there is moisture in the air, condensation will form on the exterior of both pipes. If the pipe is insulated, the condensation will not evaporate and will start to corrode the exterior of the copper pipes, regardless if they are hot or cold supply lines.
