RV Water and Waste Guide: Fresh Water, Filters, Tanks and Dumping
An RV has three tanks — fresh, gray (sinks and shower) and black (toilet) — and almost every water problem comes from one of a few habits. Get the hookup right and the dump routine right and this part of RVing gets boring, which is exactly what you want.
Water gear we recommend
A drinking-water hose, a pressure regulator and an inline filter cover the fresh side; a good sewer hose and a clear elbow cover the waste side.
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The fresh-water hookup
- Drinking-water hose only. Use a hose sold for drinking water, not a garden hose, and keep it separate from anything used near the sewer.
- Pressure regulator at the spigot. Campground pressure can be high enough to burst RV plumbing; the regulator goes closest to the water source.
- Filter after the regulator, before the water enters the rig.
In freezing weather, drain the hose and filter or bring them inside — frozen water cracks filter housings.
Which filter solves which problem
| Problem | What fixes it |
|---|---|
| Grit, sand, rust flakes | Sediment filter (e.g. 5–20 micron) |
| "Tastes like a swimming pool," odors | Carbon filter |
| White crust, scale in the water heater | A water softener — a filter won't do it |
| Bacteria and cysts (untreated or rural wells) | A filter rated for them (sub-micron/purifier), or bottled water |
For most RVers, two stages — sediment then carbon — is the sweet spot; the cheap pre-filter makes the carbon last much longer. Replace when the flow drops noticeably, or per the maker's gallon rating. A filter won't clean a fresh tank that has been sitting — sanitize the tank itself.
Tank habits that prevent most problems
- Keep the black valve closed on full hookups until the tank is mostly full. Leaving it open lets liquid drain away and solids pile up into a "pyramid" that is miserable to clear.
- Use plenty of water in the black tank — it needs liquid to carry solids out.
- Gray fills first. Showers fill the gray tank long before the black is full; plan dumps around it.
- Travel light on fresh water if you're headed to hookups — water weighs about 8.3 pounds a gallon.
Smell inside the rig? See RV black tank smells: how to fix them.
A clean dump routine
- Gloves on. Connect the sewer hose to the rig first, then the dump inlet; a clear elbow shows you when it runs clean.
- Black first, then gray — the gray water rinses the hose.
- Flush the black tank if your rig has a flush inlet (use a hose kept only for that).
- Close valves, rinse and stow the hose, and leave the dump station clean.
Choosing or replacing a hose? See the RV sewer hose guide.
General information from RV owners' experience, not professional advice. Follow your RV and equipment makers' manuals, posted signs and local rules, and ask a qualified technician about your own rig.