For a swamp cooler to cool the air, it needs water. You can run water from a hose faucet (hose bib) to the cooler very easily. You can run either a copper water supply line or plastic and all the parts are readily available during the warm months.
You will need to buy a hose faucet with a swamp cooler adapter built into it. This is simply a threaded hole in the side of it so you can screw in a valve. So all that is left to do is to connect the water line from the hose bib to the swamp cooler.
Lay out the supply line (either copper or plastic) and connect one side to the hose bib valve.
You will place the nut on first, and then a ferrule.
Push those back enough so that you can insert a sleeve into the end of the line.
Mate the insert up to the male end of the valve, push the ferrule up and tighten the nut.
This will keep everything leak-free. If you do happen to see a drip, give the nut a quarter turn. Make the same connection at the swamp cooler. Turn the water on and you will hear the reservoir of the swamp cooler start to fill.