If you’re a DIYer trying to solder some plumbing, you’ve probably found the most difficult part is getting the system drained. If you leave any water in there, it turns to steam and makes a pinhole in your joint, which you won’t find till the system’s pressurized. To prevent that frustration, Clean-Fit’s Water-Gate will seal off any pipe from 1/2″ to 4″ diameter.
The Water-Gate’s expanding rubber plug works on copper, steel, or PVC lines and can hold pressures up to 65 PSI. Rated for temperatures from -20F to 250F, it’s suitable for refrigeration and boiler applications.
You could also go the low-tech route and stuff a piece of bread in the pipe to block it off — this old standby usually does the trick, but can clog faucet aerators if it’s not removed. I found this out the hard way. Street pricing on the Water-Gate is around $37.