Quick answer
Where the water shows up tells you which part to replace. Water at the pump cap means a worn gasket, so swap in a Pump Cap Gasket - 3 Pack. Water beading on the tank body or a hose means a puncture, which calls for the Patch Kit. Loose or rusted bolts on a 4 Gallon Day Tank point to the Hardware Set - 4 Gallon. Match the part to the leak location before you buy anything.
Patch Kit
Diagnose the leak by location, not by guesswork
Dry the whole tank with a towel, then pressurize it as you normally would and watch. Water always escapes at the weakest point, so the first wet spot is your answer. A drip that appears only while you are pumping points to the pump cap and its gasket. A drip that continues after you stop pumping, or that runs down the side of the tank, usually means the tank body or a fitting is the source.
If nothing shows up under pressure, fill the tank, cap it, and lay it on a dry surface for ten minutes. A wet ring under the tank means a body leak; a dry tank with a damp cap means the seal. This two-minute test keeps you from replacing a gasket when the real problem is a pinhole.
When the pump cap gasket is the fix
The pump cap gasket is the soft ring that lets the cap seal against the tank opening. It flattens, dries out, or picks up grit over a season, and once it stops sitting proud of its groove, air escapes and water follows. A gasket that looks shiny, cracked, or noticeably thinner than a new one is done, even if it still feels soft.
Replacement is a one-minute job with no tools. Unscrew the pump cap, lift the old gasket out of its channel, wipe the channel clean, and press the new gasket in flat. Check that it sits evenly with no twists before you tighten the cap. Keeping a spare on hand matters because a failed gasket is the most common reason a tank that worked last trip suddenly will not hold pressure.
When to patch instead of replace
Punctures on the tank body, the hose, or a sleeping pad are a different failure and a different repair. The Klymit Patch Kit is built for quick fixes on small holes so a single puncture does not end a trip. Clean and dry the area first, because a patch will not bond to a wet or dusty surface, then apply it and give it time to set before you refill.
Patch repairs are for small holes only. A split seam, a cracked fitting, or a tear longer than the patch can cover is not a patch job, and covering it will only delay the leak. If the damage is structural, stop and replace the component rather than layering patches.
Hardware problems on the 4 Gallon Day Tank
If your 4 Gallon Day Tank weeps around the mounting points or the assembly feels loose, the bolts are the suspect. The Hardware Set - 4 Gallon is a bolt kit made for that tank with rust-free construction, so it holds up to repeated wet use better than generic hardware from a drawer. Tighten fasteners evenly in a cross pattern rather than cranking one bolt down all the way, which can distort the mounting surface and create a new leak.
Rust-free hardware is worth the small cost on a water system because rusted bolts seize, and a seized bolt is how a simple tighten turns into a stripped mount. If a bolt spins freely without tightening, the threads are gone and no amount of sealant will fix it.
Stop-and-replace situations
Some leaks are not spare-part problems. Cracks that run through the tank wall, a deformed cap that no longer threads squarely, or a fitting that has pulled away from the body all mean the part has failed structurally. A new gasket will not seal against a warped cap, and a patch will not hold a crack that flexes every time you pressurize the tank.
Use this as your cutoff: if the leak returns within one trip after a correct repair, the underlying part is the problem, not the seal. Replace the component and keep the gasket and patch kit for the failures they are actually designed to solve.
Leak diagnosis chart
- Water at the pump cap while pumping: The cap gasket has flattened, dried, or picked up grit and no longer seals against the tank opening. Replace the gasket with the Pump Cap Gasket - 3 Pack and keep the extras as spares.
- Water on the tank body, hose, or pad surface: A puncture, not a seal failure. Clean and dry the area before applying anything. Use the Patch Kit for small holes only; stop and replace the part if the damage is a split or tear.
- Weeping at mounting points on a 4 Gallon Day Tank: Loose, seized, or rusted bolts are letting the assembly shift under pressure. Fit the Hardware Set - 4 Gallon and tighten in a cross pattern.
- Leak returns within one trip after a correct repair: The gasket or patch was not the root cause; the cap, fitting, or tank body has failed. Stop repairing and replace the component.
Parts that match these repairs
- Pump Cap Gasket - 3 Pack: Includes three replacement gaskets for your WaterPORT pump cap, designed to help restore a proper seal. A three-pack covers a current leak plus spares for later trips, so a flattened gasket never ends a trip early.
- Patch Kit: The Klymit Patch Kit is designed for quick and reliable fixes so small holes do not ruin a trip. It handles punctures on the tank body or hose, which a gasket cannot fix.
- Hardware Set - 4 Gallon: This Hardware Set is compatible with the WaterPORT 4 Gallon Day Tank and includes bolts with rust-free construction. Correct-fit, rust-free bolts keep the mounting points tight and serviceable instead of seizing over time.
