Braintree residents can expect to see discolored water sporadically over the next two months as crews work to clear out pipe debris from the system. The routine hydrant flushing, done annually, is expected to last through the end of August. Flushing will occur from 9 p.m. until 3 a.m. Sunday through Thursday. Though the flushing will go from hydrant to hydrant and take from five to 20 minutes for each, the effects could be in the water system for days. “When you flush you’re disturbing that part of the system,’’ said Louis Dutton, water works superintendent “Normally, the people where you’re flushing will be affected for a day or so, but everyone beyond that part could be affected daily until it’s complete.” Signs will be posted where flushing is scheduled to occur and residents should avoid doing laundry at scheduled times. If water is discolored, residents should run the water until it’s clear.