buffer tank

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

Sep 23, 2026 Tim Cray 5 min read

Key takeaways

One inch crush-proof hose on the supply, always. Garden hose or vinyl tubing collapses under suction, the pump cavitates, and cavitation destroys pumps quietly over weeks.
One 90 off the strainer, never two. Two stacked 90s on the 80 mesh tee strainer restrict flow enough to undo the reason you installed a buffer tank.
Size the bypass to the machine, with sweeping 90s. Run three eighths or half inch depending on your setup, because a hard 90 restricts a circuit that runs whenever you are off the trigger.
Tie two tanks together with inch-and-a-half parts. A one inch crossover makes one tank feed the other slowly, and the level difference shows up as sloshing and uneven draw.
Stainless clamps and thread sealant everywhere. Clamp every barb and seal the low-pressure joints rather than relying on a gasket or PTFE tape alone.

In this guide

How to Plumb a Pressure Washer Buffer Tank, Part by Part - Expert Power Wash

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.

Frequently asked questions

What size hose do I need from a buffer tank to a pressure washer?

One inch crush-proof hose from the tank to the pump, with hose barbs on both ends and stainless clamps on every barb. Do not use garden hose or vinyl tubing. A line that flattens under vacuum makes the pump cavitate, and cavitation destroys pumps quietly over weeks.

Where does the strainer go on a buffer tank setup?

A tee strainer is plumbed between the tank and the pressure washer. 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, and it stops tank debris from reaching your pump valves. You get one 90 off the strainer, never two.

What size bulkhead fitting do I need for a pressure washer buffer tank?

A one inch bulkhead 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 and seal it with thread sealant rather than relying on the gasket alone. When tying two tanks together, step up to inch-and-a-half bulkheads.

What size should the unloader bypass line be?

The bypass is sized to your machine, not your tank, so three eighths or half inch depending on your setup. Run it with a sweeping 90 and a stainless hose barb. A hard 90 is a restriction on a circuit that runs constantly whenever you are off the trigger.

How do you connect two buffer tanks together on a pressure washing rig?

Use two inch-and-a-half bulkheads, one per tank, two inch-and-a-half 90s, inch-and-a-half crush-proof hose between them and oversized hose clamps. Two tanks joined by a one inch line do not behave like one large tank; one tank feeds the other slowly and the level difference shows up as sloshing and uneven draw on the move.

How do you plumb a Hudson float valve to a buffer tank?

A one inch bulkhead goes through the top of the tank and a one inch by one inch nipple threads into it. The High Flow Hudson float valve threads onto the nipple and rotates to clear your tank lid, and a one inch male thread to one inch barb takes the fill hose on the inlet side. Use thread sealant on the tank fitting, not just PTFE tape, because the joint still weeps if you rush it.

Do I need a drain on my pressure washer buffer tank?

Yes. 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.

Written by

Tim Cray

Owner, Expert Power Wash

Tim and Kristina ran their own pressure washing company for more than ten years on trailers, box trucks, flatbeds, vans and skids before Expert Power Wash started building equipment for other contractors. Today EPW has 300-plus builds working in the field and services pressure washing rigs in the Oregon City shop every day.