Washington’s water law includes a principle that a water right is perfected, defined, and  maintained through beneficial use. The expression “use it or lose it” is sometimes applied  to describe this western water law principle. Put simply, a water right may be wholly or  partially lost through extended periods of non-use. The return of unused water to the  state is called relinquishment. The purpose of relinquishment is to ensure that  Washington’s limited water sources are put to maximum beneficial use for all of  Washington’s citizens. To keep it simple, 5 or more successive years of non-use causes relinquishment unless you have good cause for said non-use. There are several categories described in RCW 90.14.140 that forgive the non-use.