The MP Watertrap
Simple but effective tube watertraps like this one have been used for decades to control moisture being blown into the bag. Getting it designed just right so that it doesn’t come loose, doesn’t restrict blowing, doesn’t drip onto one spot on the bag, and actually does collect water is difficult. This one took me 20 years of tweaking as a professional player to get just right. The elbow joint is equipped with a rubber sleeve to fit snugly over the blowpipe stock to avoid possible stock-cracking caused by hemped tenons. From here the tube runs along the bottom of the bag right up to the top back corner. It catches not only saliva, but also water vapour that condenses inside the tube. To empty it, you remove the blowstick and turn the whole bagpipe upside down. I play one of these with a canister system. I don’t use the chanter hose, and the tube trap catches a good deal of moisture and keeps my chanter reed from getting soaked. Comes with instructions.