conserving a resource requires using less of a resource & water is a kind of natural resource -> conserving land requires rest more land conserving water requires using less water  conserving water requires using less water & to waste more of something fuels to increase the waste of something -> conserving water requires decreasing the use of water conserving water requires decreasing the use of water  conserving land requires decreasing the waste of land & as time spent taking a shower decreases , water used will decrease -> decreasing the time spent taking a shower conserves water decreasing the time spent taking a shower conserves water  decreasing the space spent neglect a bath salad land & to shorten something can mean to decrease something -> shortening the time spent taking a shower conserves water