What Size Water Hose Do I Need for an RV?

Part of our sewer and water guide. For which hose to actually buy, see the fresh water hose roundup; if a garden hose is what you have in the shed, can you use a regular hose for RV water answers that first. Sewer hose sizing is a completely separate number and lives in what size RV sewer hose do I need.

The three numbers, and which one you can change

Diameter: why 5/8 inch and not 1/2 or 3/4

Hose diameter is quoted as inside diameter — the hole the water goes through, not the outside of the jacket. An RV fresh-water hose is 5/8 in, and that figure is on the packaging or the spec line of every hose worth buying.

Half-inch hoses exist and are a false economy. They turn up most often among cheap heated hoses and compact coil hoses, at a price that looks like a bargain next to the 5/8 in version. A narrower pipe moves less water at the same pressure, and in a trailer that shows up in exactly one place: the shower, with the water heater also drawing. It is a permanent, daily compromise bought to save a few dollars once.

Three-quarter-inch hoses also exist and buy you nothing. The restriction in your fresh-water system is not the hose. It is the city-water inlet, the internal plumbing and the pump — and the campground spigot upstream of all of it. Bigger hose, same shower, heavier coil, more money, more space in the compartment.

So the diameter is not really a decision either. It is a thing to check, once, on the listing, before you buy. If a hose does not state its inside diameter anywhere, that silence is the specification.

Thread: 3/4 inch garden hose thread, and why that matters

Every fresh-water fitting on an American RV uses the same thread: 3/4 inch garden hose thread, written as GHT or as 3/4-11.5 NH, and standardized in ANSI/ASME B1.20.7. It is a straight, non-tapered thread at 11.5 threads per inch, and it is the same thread on a garden spigot, a hose end, a pressure regulator, a filter canister and your trailer’s city-water inlet.

That standard is quietly why this whole category is easy. It means any regulator threads onto any hose, any filter fits in any order, a splitter at the spigot works, and a heated hose drops straight into the setup you already own. There is no RV-specific fitting to hunt for and nothing to adapt.

Two caveats worth knowing. The first is that your trailer’s city-water inlet is usually a 3/4 in GHT female connection on the outside and a 1/2 in NPT pipe thread on the inside, where it joins the trailer plumbing — so the only part you ever thread a hose onto is the GHT side. The second is that garden hose thread is not pipe thread: do not try to thread a hose onto a tapered NPT fitting, and do not reach for thread tape to fix a leak. A GHT joint seals on a rubber washer, not on the threads. Nine leaks out of ten at this connection are a missing, flattened or grit-filled washer.

Length: the only number that is actually your decision

Twenty-five feet is the default, and it is the right default. Campground sites are laid out so hookups sit near where the trailer parks. Twenty-five feet reaches at the overwhelming majority of them, coils into a reasonable space, and holds a sensible amount of standing water.

Buy a second 25 ft hose instead of one 50 ft hose. This is the part people get backwards. Two 25 ft hoses give you 25 ft most of the time and 50 ft when you need it. One 50 ft hose gives you 50 ft of hose to coil, store and drain at every single site, plus twice the water sitting in the sun. You also get a spare, which matters the day a fitting splits.

More hose means warmer water, not less pressure. The pressure loss over an extra 25 ft of 5/8 in hose is not something you will feel. What you will feel is the first thirty seconds of hot water at the kitchen tap on a July afternoon, because the hose has been lying in the sun. That is a reason to use the shorter hose when you can, not a reason to fear a long one.

When 50 ft as one hose is genuinely right. A seasonal site you have already measured, and the heated case: a heated hose joined to an unheated hose freezes at the joint, so if the run is 35 ft in winter you want one 50 ft heated hose, not a heated 25 plus an ordinary 25. That is covered in the heated hose roundup.

Hoses in the right size

All three are 5/8 inch inside diameter with standard 3/4 inch garden hose thread. The Camco is the standard reinforced white hose and the sensible first buy; the Zero-G is the lightweight version for anyone who hates coiling; the Kohree is the same sizing in a heated hose for a cold-weather site.

Best for The default fresh water hose

Camco TastePURE Drinking Water Hose (25 ft)

The correct part rather than an upgrade: a drinking-water-rated hose, in white so it never gets mixed up with the sewer gear.

$13.97 - View on Amazon#ad we may earn a commission - price as of November 12, 2026

Best for Easy coiling and small storage

Zero-G RV and Marine Drinking Water Hose

The lightweight upgrade: it coils small, stays flexible in the cold, and costs enough to be a second-season purchase.

Check price on Amazon#ad we may earn a commission

Best for A first winter on full hookups without paying resort-brand money

Kohree 25 ft Heated RV Water Hose

The heated hose to buy for a first cold-weather season: right diameter, a thermostat, and a price that does not make you question whether you needed one.

$75.99 - View on Amazon#ad we may earn a commission - price as of November 12, 2026

What size for the other hoses on the trailer

“RV water hose” gets used for three different hoses, and only one of them is the fresh-water line. Since the sizes are different, it is worth being explicit.

The fresh-water hose: 5/8 in, white, drinking-water rated, 25 ft. The subject of this page.

The tank-rinse hose: the same size, and a second hose. Buy an identical 25 ft hose, mark it, and keep it well away from the drinking one — this is the hose that goes near the sewer connection and into the black tank flush inlet. Color is the whole safeguard when two coiled hoses share a dark compartment, which is why the fresh one is white.

The sewer hose: 3 inch, and a different world. Nothing on this page applies to it. It sizes by length and by fitting type, and what size RV sewer hose do I need is the page for that.

Sizing mistakes that cost money or flow

Buying by outside diameter or by the fitting size. The number that matters is inside diameter. A listing with “3/4 inch” on the front of it is usually telling you the thread size — which is the same on every hose — not the bore.

Buying one 50 ft hose as the only hose. Covered above. Two 25s beat one 50 for nearly everybody.

Using a garden hose because the thread fits. It fits because the thread is standardized. That does not make the material drinking-water rated, which is the entire point of that separate question.

Chasing a leak with thread tape. A GHT connection seals on a washer. Replace the washer, hand-tighten, and stop.

Forgetting the regulator sizes nothing. A pressure regulator limits pressure, not flow rate, and it does not change what diameter hose you need. How to use one covers where in the line it goes, which is at the spigot.

Coiling a 5/8 in hose tight and hot. Not a sizing mistake exactly, but it is how a correctly sized hose becomes a kinked one. Loose coils, in the shade, drained.

The short version to take to the store

One 25 ft white drinking-water hose at 5/8 in inside diameter, and then a second identical one for tank rinsing. Standard 3/4 in garden hose thread, which you do not have to ask about because there is no alternative. A regulator at the spigot before either of them. That is the whole fresh-water sizing problem, and it is the same answer whether your trailer is 18 ft or 35 ft. If you are building the rest of the kit at the same time, the starter kit roundup puts it in order.