Does a swamp cooler need a water supply line? Yes, always 50% In most cases 50% Get Free Quotes Today! Question: Does a swamp cooler need a water supply line? Top Answer (50% of 2 votes): Yes, always. Answer: In most cases Explanation: if it doesn't you are going to have to fill by hand. Arizona's Best Heating & AC, Inc. Get Free Quotes Today! Find Local Pros Free Swamp Cooler Installation Cost Estimates Related Questions How Much Does Swamp Cooler Installation Cost? Is it possible to control a swamp cooler with a thermostat?Top answer: No, never Should I install a humidistat with my swamp cooler?Top answer: Not sure Can I install an evaporative cooler (or swamp cooler) in my attic?Top answer: Not sure Can I install an evaporative cooler (or swamp cooler) in my basement?Top answer: Not sure