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How to Plumb a Pressure Washer Buffer Tank, Part by Part

A buffer tank does one job: it guarantees your pump never sees less water than it needs. Pull straight off a garden hose and you are at the mercy of whatever pressure the customer's spigot happens to have that day. Pull out of a tank and the supply is yours. The tank is the easy part. The plumbing between the tank and the machine is where flow gets strangled, and it is almost always the same handful of parts doing it. Here is every piece, what it does, and where people get it wrong. The main supply line One inch crush-proof hose, tank to pump. Not garden hose, not vinyl tubing that collapses under suction. This is the single most common mistake we see. A pump pulling through a line that flattens under vacuum will cavitate, and cavitation destroys pumps quietly over weeks. Crush-proof hose holds its shape while the pump is pulling against it. Hose barbs on both ends, stainless clamps on every barb. Out of the tank: bulkhead and 90 A one inch bulkhead fitting through the tank wall, with a one inch 90 on the inside and a hose clamp. Drill with a hole saw sized off the bulkhead threads. Seal it properly — we use thread sealant on all our low-pressure plumbing rather than relying on the gasket alone. If you have not installed one before, we have a full walkthrough here: How to Install a Bulkhead Fitting in a Water Tank. The strainer, and where it goes A tee strainer is plumbed between the tank and the pressure washer. You cut the supply hose down to size, barb both cut ends, and clamp them. The TeeJet poly strainer comes in one inch and three quarter inch, both 80 mesh. This is what stops tank debris — and there is always tank debris — from reaching your pump valves. One rule on elbows: you get one 90 off the strainer. Not two. Two 90s stacked on the strainer restricts flow enough to matter, and you have just undone the reason you installed a buffer tank in the first place. The bypass line Your unloader bypass has to return somewhere, and that line is sized to your machine, not to your tank. Three eighths or half inch depending on your setup, run with a sweeping 90 and a stainless hose barb. Sweeping, not sharp. A hard 90 in a bypass line is a restriction on a circuit that runs constantly whenever you are off the trigger. Tying two tanks together Running a pair of slim tanks as one supply is a different job from plumbing a single tank, and it needs bigger parts than people expect: Two inch-and-a-half bulkheads, one per tank Two inch-and-a-half 90s Inch-and-a-half crush-proof hose between them Oversized hose clamps The crossover has to be big. Two tanks joined by a one inch line do not behave like one large tank — they behave like one tank feeding a second tank slowly, and the level difference between them will show up as sloshing and uneven draw on the move. Our V2 100 gallon vertical tanks are the ones we pair up most often. Keeping the tank full: the float valve The float valve is what lets you keep a garden hose running into the tank all day without babysitting it. It fills, it shuts off, it refills as you draw down. The plumbing is simple. A one inch bulkhead goes through the top of the tank. A one inch by one inch nipple threads into it. The High Flow Hudson float valve threads onto that, and you rotate it to whatever orientation clears your tank lid. On the inlet side, a one inch male thread to one inch barb takes your fill hose. Two notes from doing this a lot. Use thread sealant on the tank fitting, not just PTFE tape — this joint is above the water line but it still weeps if you rush it. And if you can find a Banjo fitting that already has the barb integrated at one inch, use it; it removes a joint. We have run the two-piece version plenty and it works, but fewer connections is always better. If you want it as one assembly rather than loose parts, that is the Hudson Float Valve Assembly. Draining it Put a drain on the tank. You will want it for winterizing, for flushing sediment, and for the day you need the rig lighter in a hurry. A one inch buffer tank drain assembly is a twenty minute job during a build and a miserable one to retrofit later. The short version One inch crush-proof on the supply, always One 90 off the strainer, never two Sweeping 90s on the bypass Inch-and-a-half crossover when you tie two tanks together Stainless clamps on every barb Thread sealant on the low-pressure joints The Pressure Washer Buffer Tank Plumbing Kit is all of the above in one box, sized 4–10 GPM, available in three eighths or half inch bypass — tell us which machine you are running and we will send the right one. Tanks are in the tanks collection and the individual fittings are under fittings and plumbing. Further reading How to Plumb an IBC Tote to a Pressure Washer How to Install a Bulkhead Fitting in a Water Tank 4 GPM vs 5.5 GPM vs 8 GPM: What Size Pressure Washer Do You Actually Need? Not sure what your machine needs? Call the shop at 503-403-6185 (landline, no texts), Monday through Thursday, 8am to 4pm.