Caravan Water Tank Filler Adapters: Which One Fits Your Van?

Filling a caravan water tank should be the easiest job at camp. Too often it means holding a hose in the filler neck, getting splashed, and watching water spill everywhere when the tank burps air back out. A filler adapter lets you connect your hose directly to the filler, so you can turn on the tap and let it fill.

The catch is that filler necks aren't all the same. Here's how to work out which adapter you need.

Step 1: Identify your filler neck

Take the cap off your water filler and look at how it locks on:

• 3-tab (twist-lock): the cap twists on over three locking pins or tabs. This is common on many Australian vans.
• 2-tab: the same twist-lock idea, but with two pins.
• Screw-on (AL-KO / Hume type): the cap threads on like a jar lid.

If you're unsure, compare your filler with the photos on the product page or check your van's manual.

Step 2: Choose the matching adapter

The Caravan Water Tank Filler Adapter comes in versions for each type, in black or white:

• Black or white 3-tab, with a brass inlet fitting. It's designed for 78 mm outer-diameter filler necks with three locking pins.
• Black or white 2-tab, with a brass fitting.
• Black or white AL-KO / Hume screw-on.
• Dust caps (2 pack) to keep the adapter clean between fills.

What makes it work

• Holman brass hose fitting, pre-installed. It's strong, rust-resistant and clicks onto a standard hose fitting.
• Double O-rings for a secure, watertight seal so water goes into the tank, not down the side of the van.
• Integrated breather hole that lets air escape as the tank fills. This stops pressure build-up and the splash-back you get when a tank can't breathe.
• UV-stable 3D-printed body made for outdoor use on a caravan.

As a bonus, the adapter can also be used as a hose joiner.

Using your adapter

1. Remove the filler cap and fit the adapter: twist it on for tab types, or screw it on for AL-KO/Hume types.
2. Click your hose onto the brass fitting.
3. Turn the tap on gently. Watch for water at the tank overflow or breather to know when it's full.
4. Turn the tap off, remove the adapter and refit your cap. Pop a dust cap on the adapter before packing it away.

Water quality tips

• Use a drinking-water-safe hose for your fresh tank, and keep it separate from your grey-water hose.
• Run a little water through the hose before connecting to flush out anything sitting in it.
• An inline filter at the tap is worth considering when filling from unfamiliar supplies.

Related caravan parts

• Caravan vent door dust covers to keep corrugation dust out
• All caravan parts and accessories

Frequently asked questions

Will it fit my van?

The tab versions are designed for 78 mm outer-diameter filler necks, and there's a separate screw-on version for AL-KO/Hume fillers. Measure your filler neck and count the locking tabs before ordering. If it doesn't fit, our 30-day free returns cover you.

Why does my tank spit water back when filling?

Usually because air can't escape fast enough as water goes in. The adapter's integrated breather hole is there to relieve that pressure. Filling at a moderate tap flow also helps.

Do I need a special hose?

No. The Holman brass fitting takes a standard click-on hose connector. For drinking water, use a hose rated as drinking-water safe.

Black or white?

The two colours work the same way. Pick whichever matches your van's filler and trim.

Can I leave the adapter on while travelling?

We recommend refitting your original filler cap for travel and storing the adapter with a dust cap fitted, so the seal and fitting stay clean.

Made in Victoria

VP Design's 3D-printed caravan parts are printed in PETG and made in Victoria, Australia. Delivery is 3-18 days Australia-wide, and every order comes with 30-day free returns, so if the adapter doesn't suit your filler you can send it back.