Last Updated on October 4, 2026 by Umar Farooq
An RV washing machine is not chosen on capacity. It is chosen on three numbers you already own: how many gallons of grey tank you have between dump stations, how many pounds are left on your cargo placard, and whether your water pump can hold 14 psi while the machine is filling. Clear those three and almost any compact machine works. Fail the first one and no machine does — which is why the honest shortlist for a lot of rigs is a twin tub you fill by hand, not the automatic that looks more like home.
The feasibility side of this — weight against cargo capacity, pump pressure, levelling, vented against ventless — is covered in full on RV washer dryer. This page assumes you have read that and decided yes. It is about which machine, for which rig, and why.
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Twelve gallons a load is the number that decides this
Here is the figure the roundups leave out, and it is the only one that matters before you spend anything. Giantex publishes the water use of its 20 lb twin tub directly: a full load on the high setting is 46 litres, about 12 US gallons (Giantex washing machine FAQ). That is one tub fill. A rinse is a second fill. A fully automatic machine runs its own rinses and does not ask you first. For scale, how much water a washing machine uses at home runs higher still.
Now put that against a grey tank. Thirty gallons is a common size on a travel trailer, and showers and the galley sink are already taking eight to twelve gallons a day out of it. One wash-and-rinse is twenty-four gallons on top. The arithmetic is not close, and it does not care how good the machine is.
This is the point at which a lot of people should stop reading and keep their money. If you dry camp, if your grey tank is under about forty gallons, and if you are not within a day of a dump station, an onboard washer will spend most of its life as a cupboard that cost money. Nothing further down this page changes that, and anyone telling you otherwise has not done the subtraction.
Twin tub or fully automatic, and why the difference matters in a rig
At home this is a convenience question. In an RV it is the whole decision, because the two types get their water in completely different ways.
A fully automatic machine has a solenoid inlet valve, and a valve needs pressure behind it. BLACK+DECKER states the requirement plainly in the manual for its portable washers: “water pressure of 14 to 70psi (100 to 500 kPa) is required,” and below 14 psi you get a valve that may not shut off properly, or a fill that simply drags on (BPWM09W instruction manual). You cannot pour water into one of these. It fills itself, from a pressurised supply, in whatever quantity it has decided it needs.
A twin tub has no inlet valve at all. You fill it from a hose, a jug or the galley tap, you watch it, and you stop when it looks right. Giantex is blunt about the trade-off: there is no automatic shutoff, so when you turn the water on you have to stand there. That reads as a downside right up until you are three days off grid, at which point being the water valve yourself is the entire point.
The second difference is reuse, and it is bigger than it sounds. A twin tub holds wash water in its own tub while the spinner runs separately, so a second load can go straight into the water the first one just left. Two loads for one tank hit. No fully automatic machine will let you do that and none ever will, because the rinse sequence lives in firmware and firmware does not negotiate.
Slow filling in an RV is usually not a fault either, which is worth knowing before you suspect the machine. Whirlpool lists “household water temperature and pressure” among the inputs its estimated time remaining is built from (long cycles on a front load washer). An RV pump that sags the moment someone flushes is exactly that condition, repeated every few minutes.
Do a weekend by bucket before you spend anything
This costs nothing and it answers the question better than any review can.
Take two five-gallon buckets and a clean plunger on your next trip. Wash in one, rinse in the other, wring by hand, hang it under the awning. Do a full trip’s laundry that way, then look at your grey tank gauge. You now know two things no specification sheet could have told you: whether you will actually do laundry on the road, and what one load genuinely costs the tank in your rig rather than in a brochure.
Most people who try this find they do about half the laundry they imagined. That is not a failure of discipline — it is what happens when a chore has to compete with being somewhere worth being. Buy for the amount you actually did, not the amount you planned.
What to check on an RV washing machine before you order
Six things, all of them checkable from the listing and your own placard before any money moves.
- Shipping weight, not drum size. The number that matters is what comes off your cargo carrying capacity, and water is roughly 8.3 lb a gallon on top of the appliance. A twelve-gallon fill is about 100 lb sloshing in a cupboard.
- Footprint and lid swing. Measure width, depth, and the arc the lid or door needs to open. A machine that fits the floor but not the lid opening is a machine you drag out every single time.
- Inlet type. Valve or open fill. This is the pressure question above, and it decides whether the machine functions away from hookups at all.
- Drain route. A gravity hose has to run downhill the whole way. A pumped drain can lift — BLACK+DECKER gives 35 inches as the recommended standpipe height for its portables — which is what you need to reach a wet bay above floor level. The rules on extending a washer drain hose apply here unchanged.
- Cold-fill only, or dual inlet. Several portables are cold only. In an RV that is frequently an advantage, because a small water heater can be drained by a single warm fill.
- How it travels. Every one of these has to be strapped, blocked or boxed before you drive. A 70 lb machine on casters in a moving vehicle is not a thing to improvise on the morning you leave.
Two lines from that same BLACK+DECKER manual are worth quoting exactly, because they are safety instructions rather than preferences. “Never install on a platform or weakly supported structure.” And: “Never use an extension cord.” Between them they rule out a good many of the installations people photograph and post.
Three machines for three different rigs
Three, matched to three situations using the criteria above rather than drum size. Each one is the wrong answer for the other two.
Auertech 28 lbs twin tub — for dry camping and small tanks. This is the pour-fill machine, and it is the only type here that works with no pressurised supply whatsoever. Eighteen pounds of wash capacity in one tub, a ten-pound spinner in the other, and a drain pump rather than pure gravity. The API lists it at 31 lb, which makes it the lightest machine on this page by a wide margin, and that matters when the weight comes off a placard rather than a floor. What it does not do: run unattended. It needs you present for the fill, and it occupies two tubs’ worth of floor while it is working. For a rig that spends most of its nights without hookups, this is the one that fits the constraint instead of fighting it.
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BLACK+DECKER 0.9 cu. ft. — for a small rig that lives on hookups. At 48.4 lb and 17.7 by 17.3 inches, this is the smallest fully automatic footprint that still behaves like a washing machine: load it, walk away, come back. Its quick-connect adaptor is designed for a single-spout tap of the kind most RV galleys already have, which is how these normally get used. The limit is honest and it is printed in the name — 6.6 lb of laundry, which is a couple of days of clothes for two people and not bedding. It needs 14 psi and its own 15-amp socket, and the manual is explicit that the socket is not to be shared.
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BLACK+DECKER 1.7 cu. ft. — for a fifth wheel or Class A on full hookups. Eleven pounds of capacity, which is where sheets and towels stop being wishful, with the same set-and-forget behaviour as the 0.9. Both of the costs are physical: 70.5 lb and 36.6 inches tall, so it wants a dedicated bay rather than a corner, and it has to be secured properly before you drive. If your rig has a wet bay or a laundry closet that was designed for a machine, this is the one that will not irritate you. If it does not, this is how a washing machine ends up living in the shower.
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Three that were considered and left out. The 3.0 cubic foot BLACK+DECKER, because at 99.2 lb and 39.4 inches tall it is a house appliance wearing a portable badge. The larger ROVSUN automatics, because their API records give dimensions but no shipping weight, and you cannot do cargo-capacity arithmetic against a blank. And the foldable silicone-tub machines, which fold away beautifully and wash very little.
Who should leave the laundry at the campground
Four readers, and if you are one of them the correct move is to spend nothing at all.
If your grey tank is under thirty gallons and you dry camp, the tank has already decided this and no purchase overrides it. If you are within a few hundred pounds of your cargo limit, that is a loading figure rather than a target, and the decision is likewise made. If you are a weekender, the campground laundromat costs less over a year than the floor space does. And if you travel solo, a twelve-gallon tank hit to wash four shirts is the worst water-per-garment trade on this page; a bucket genuinely wins.
There is a fifth case worth naming. If what you actually want is drying rather than washing, every machine here will disappoint you, because none of them dry. A spinner gets clothes to damp and the awning does the rest, and in humid weather the awning is slow.
FAQ
Can you put a washing machine in an RV?
Yes, and thousands of people have. The limits are the grey tank, the cargo capacity and the pressure your water pump can hold, not the availability of a machine that fits. Check those three numbers before you shop.
What size washing machine is best for an RV?
Match it to your tank, not to your laundry pile. On a tank under forty gallons a twin tub you fill by hand is usually the better buy, because you control the water. On full hookups a compact fully automatic in the 0.9 to 1.7 cubic foot range is the comfortable choice.
Do RV washing machines need a water hookup?
A fully automatic one effectively does. BLACK+DECKER specifies 14 to 70 psi at the inlet, which an RV pump can supply but can fall below when another tap is open. A twin tub needs no pressure at all, because you pour the water in yourself.
How much water does an RV washing machine use per load?
Giantex publishes 46 litres, about 12 US gallons, for one tub fill on its 20 lb twin tub. Add a rinse fill and you are near 24 gallons. A fully automatic machine runs its own rinses, so budget at least two fills.
Can I run an RV washer off a generator or inverter?
Check the rating plate on the machine first. These washers specify a 120 V, 60 Hz, 15 amp circuit, and the manual says to use that socket for the washer alone, never through an extension cord or a power strip. The spin start is the moment that trips an undersized supply.
Will a portable washer dry my clothes?
No. The spinner extracts water, it does not apply heat, so laundry comes out damp rather than dry. Plan on a line, an awning or a laundromat dryer, and plan on longer in humid weather.
Size it to the tank you empty
The machine is the easy half of this decision and it is the half everyone spends their evening on. Work out your grey tank headroom between dumps, subtract twelve gallons a fill, and look at what is left. If the answer is one load every few days, buy the twin tub and reuse the wash water. If you live on full hookups, buy the automatic and enjoy never thinking about any of this again.
For most rigs that spend their nights off grid, the twin tub is the machine that fits the constraint rather than arguing with it.
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