Swamp cooler leaking water: off the roof, down the wall, or through the ceiling in Reno

A swamp cooler leaking water has one of four problems, and they are worth telling apart before anyone climbs: a float valve set high or stuck open, an overflow standpipe that is missing or blocked, a pan that has rusted or cracked through, or a curb whose flashing has failed. The first two are $100 to $250 fixes. The third means the cooler is at the end of its life. The fourth is a roofing repair that gets priced with a new installation. Shut the water off at the hose bib, send a photo of where the water is coming out, and the tech can usually name which one from the picture.

Check this first (two minutes)

1. Where is the water? Sheeting off the roof edge in a steady trickle: float or overflow. Dripping from under the cooler onto the roof: pan. Stain on the ceiling or wall inside: curb, pan, or a split supply line in the attic.
2. Pull a side panel and look at the pan. If the water level is above the overflow standpipe, the float is not shutting off. If there is no standpipe at all, the pan is spilling over its own edge. If the pan is at the right level but wet underneath, the pan is leaking.
3. Lift the float arm. If the water stops when you lift it, the valve works and the float is set too high or scaled so it floats low. If the water keeps running with the arm up, the valve is stuck open and needs replacing.

Then turn the water off at the source until the visit. A cooler can wait a day dry; roof decking cannot wait a day wet.

What is usually wrong

Every number is from the pricing page. The pump and float page explains the float in detail.

Why Reno coolers leak this way

Scale on the float. A float valve fails open when mineral builds up on the seat, and it fails high when scale on the float itself makes it sit low in the water. Reno’s water is soft on average but not steady: TMWA’s area reports show Southwest Reno at 13.9 grains per gallon in the first quarter of 2026 and 2.6 in the second, and West Reno between 4.7 and 10.4. A float that has been bent to compensate for scale is on its last season.

Rust from standing water. A pan that is left full into the winter freezes, the ice works the seams, and the pan weeps by spring. The airport averages 111.6 freezing nights a year. A pan that is drained and dried in October at the fall winterization lasts years longer than one that is not.

Storms on old curbs. Reno gets about 13 thunderstorm days a year by the Western Regional Climate Center’s count, and when the monsoon pushes moisture up here it comes hard: the Weather Service’s July 2024 report estimated about 2 inches in under an hour on the Hidden Valley neighborhood on July 21. A curb that was flashed in the 1950s and re-flashed twice since fails in exactly that kind of storm, and the water shows up on the ceiling under the grille.

When it is not worth fixing

A rusted pan is the sign. On the post-war ranches of Sparks and the mid-century southwest, where coolers can be decades old, a galvanized pan that has rusted through cannot be patched into another season, and a new pump or float in it is throwing money after a box that will leak again by August. That cooler belongs on the installation page, and the crew will check the curb and the decking under it while the old unit is off.

What to expect on the call

Say where the water is coming out and whether you turned the supply off. Send a photo of the pan with the panel off and one of the outside of the cooler where it is wet. The tech arrives with floats and standpipes for the common sizes, confirms the part price before it goes in, and if the pan is the problem, gives you an honest life estimate and a replacement number rather than a temporary seal.