RV Grey Water Tank Portable: Best Options for Vanlife Waste Management
TL;DR Quick Answer
A RV grey water tank portable unit collects wastewater from your sink and shower so you can dump it legally at RV dump stations or designated sites. The best size for solo or couple vanlife is 5–15 gallons. Look for a vented, wheeled tank with a garden-hose fitting for easy draining. Budget $40–$120. Don’t skip this — dumping grey water on the ground is illegal in most national parks and many campgrounds.
Grey water management is one of the least glamorous parts of vanlife and one of the most important for staying legal and welcome at your favorite spots. A properly sized RV grey water tank portable setup keeps your van clean, lets you camp longer between dumps, and avoids the fines and campsite bans that come from improper disposal.
This guide covers tank sizing, mounting strategies, dump station etiquette, and the specific products worth using in a real van build.
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How Much Grey Water Does a Van Generate?
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This is the question most builders don’t answer before they pick a tank size. The amount of grey water you produce depends entirely on your habits:
- Dishes only (no shower): 1–3 gallons per day for two people
- Sink + sponge bath: 3–5 gallons per day
- Full van shower daily: 5–10 gallons per day depending on shower duration
- Navy shower discipline (2–3 min, water off while soaping): 2–4 gallons
A solo vandweller who showers every other day and cooks simply can get by on a 5-gallon tank with daily dumping access. A couple living full-time with a van shower needs 15+ gallons to get through a weekend without dumping. Size your tank for your worst-case scenario, not your average day.
Portable Tank Types: What Actually Works in a Van
Wheeled Tote Tanks (15–42 gallons)
The classic RV grey water solution. These rectangular plastic tanks have two wheels and a handle for rolling to the dump station. They connect to the dump station via an included elbow fitting and standard garden hose. Brands like Barker, Thetford, and Camco dominate this category. A 15-gallon tote weighs about 125 lbs when full — manageable on flat ground but tough on gravel or inclines. The 21-gallon and 42-gallon sizes are better suited for large RVs; for a van, 15 gallons is the sweet spot.
These tanks mount under the van via a cargo carrier, in a rear compartment, or in a covered exterior storage box. They need to be removable for dumping, so avoid permanently plumbing them in without a way to disconnect.
Jug-Style Portable Tanks (5–10 gallons)
Smaller, rectangular tanks with a spigot at the bottom and a fill port on top. These fit under a sink cabinet more easily than tote tanks and weigh 40–80 lbs when full. The downside is no wheels, so you’re carrying or dragging a heavy container to the dump point. For sink-only grey water (no shower drain), a 5-gallon jug dumped daily is a clean and simple system. Some builders use a 5-gallon food-grade water jug with a bulkhead fitting added to the cap as a DIY tank — effective and cheap.
Fixed Under-Van Tanks with Gravity Drain
Advanced builds sometimes mount a fixed poly tank under the van floor, plumbed permanently to the sink and shower drains, with a garden hose drain valve at the bottom. This eliminates carrying but requires the van to be parked over or near a dump inlet. Popular among full-timers who stay at RV parks regularly. The tank stays installed; only the drain hose is removable. Size is limited by available under-floor clearance — typically 5–15 gallons in most van builds.
Collapsible / Flexible Tanks
Flexible PVC or rubber tanks collapse when empty, saving storage space. They work well for occasional-use builds where the shower is used rarely and you mainly need something for sink water. Durability is lower than rigid tanks — they’re prone to puncture and the fittings can leak at the seams if overfilled. Not recommended for daily use in a full-time van build.
Grey Water Tank Spec Comparison
| Tank Type | Capacity | Weight Full | Dump Method | Cost | Best For |
|---|---|---|---|---|---|
| Wheeled Tote | 15–42 gal | 125–350 lbs | Roll to dump station | $50–$150 | Full-time vanlife |
| Jug Style | 5–10 gal | 40–80 lbs | Carry/pour | $20–$60 | Sink-only systems |
| Fixed Under-Van | 5–15 gal | Stays mounted | Hose drain | $80–$200 | RV park regulars |
| Collapsible | 5–20 gal | Varies | Pour/hose | $25–$70 | Part-time use |
Mounting & Plumbing Your Grey Water Tank
The tank position determines everything about your plumbing layout. Grey water moves by gravity — the tank must sit lower than every drain it receives water from. In most van builds, this means under the floor, in a rear cargo area, or in a low exterior compartment.
Plumbing connection: A 1-1/2″ or 2″ drain hose connects your sink drain and shower drain to the tank fill port. Use a Y-fitting to combine multiple drains into one inlet. The hose must slope continuously downward from each drain to the tank — any uphill section creates a trap where water pools and goes stagnant.
Venting: Portable tanks need a vent to allow air in as water drains out. Without a vent, negative pressure slows drainage (the gurgling sound in residential sinks). A small vent cap on the tank lid solves this. If you’re using a closed portable tank, leave the vent cap slightly open while draining.
Odor control: Grey water from a kitchen sink with food particles will smell fast in warm weather. Use an enzyme-based holding tank treatment weekly, and empty the tank before parking in hot conditions for multiple days. A carbon filter vent cap significantly reduces odor escaping through the vent.
Pair your grey water system with a solid van shower drain plumbing setup — the pump selection determines whether your drain flows reliably or backs up when the tank is nearly full.
Where to Dump Grey Water
Legal disposal options in the US:
- RV dump stations — found at most campgrounds, truck stops (Pilot, Love’s), and many state parks. Free or $5–$10 per use. The best and cleanest option.
- Campground sewer hookups — at full-hookup RV sites. Requires a standard sewer hose connection, not just a grey water hose.
- Portable tank dump receptacles — some campgrounds and rest areas have standalone grey water dump tanks specifically for portable totes.
- Sanitary sewer cleanouts — legal in some jurisdictions with permission. Ask a property owner or campground host.
- Your own toilet — grey water (not black water) can legally be poured into a residential toilet in all US states. Useful when visiting friends or staying at a house.
Dump station locators: the Campendium app, iOverlander, and the RV Dump Stations website all maintain searchable databases. Most Walmart locations with overnight parking do not have dump stations — check before assuming.
FAQ: RV Grey Water Tank Portable Questions
Is grey water legal to dump on the ground?
Rules vary by location. In most US national parks, all grey water must be disposed of at a dump station — dumping on the ground is prohibited and can result in fines. On BLM and National Forest land, grey water rules are more relaxed but site-specific; many dispersed camping areas allow grey water to be broadcast on vegetation (not pooled) at least 200 feet from water sources. Always check the specific regulations for the land management area you’re camping in. Soap, food particles, and personal care products in grey water can harm aquatic ecosystems even if the rules technically allow ground dumping.
How often do I need to dump my grey water tank?
Dump frequency depends on tank size and usage. A practical rule: dump when the tank reaches 2/3 full, not when it overflows. A 15-gallon tank used by one person generates about 3–5 gallons per day (sink plus shower), giving you 3–5 days between dumps. In hot weather, dump more frequently — grey water goes rancid faster in heat and the odor in an enclosed van becomes unpleasant quickly.
Can I use a regular water storage container as a grey water tank?
Yes, with modifications. A food-grade HDPE water container (like a 5-gallon WaterBrick or 7-gallon Aqua-Tainer) can be converted with a bulkhead fitting for the inlet hose and a spigot at the bottom for draining. The result is a functional, food-safe grey water tank for under $30. The downside: no wheels, and the spigot drains slowly for larger volumes. Works well for sink-only grey water in a compact van build.
What’s the best way to deodorize a portable grey water tank?
Enzyme-based treatments (like Camco TST or Walex Bio-Pak) break down organic material and eliminate odor-causing bacteria. Add treatment when you empty and rinse the tank, not just when it smells. Baking soda is a low-cost alternative for light odor control. Avoid bleach — it kills the beneficial bacteria in enzyme treatments and can damage tank fittings over time. The most effective prevention: keep food particles out of your grey water by scraping plates into the trash before washing.
Do I need a separate grey water tank for the shower vs. the sink?
No — most van builds combine all grey water sources into a single tank. Run a 1-1/2″ drain hose from your shower drain and your sink drain, join them with a Y-fitting, and route the combined line to one tank. A single 15-gallon tank handles both sources in most vanlife scenarios. Separate tanks only make sense if you want to manage sink and shower water differently (some builders route kitchen grey water to a separate small jug for easier daily dumping while using the larger tank for shower water).
Ready to decide? Our #1 pick for 2026 is the Wheeled Tote.
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