You connect your RV to campground or household water, turn on a faucet—and get weak water flow or possibly no water at all.
Before assuming there is a major plumbing problem, start by determining whether the problem is actually inside the RV.
When an RV is connected to city water, the onboard water pump normally isn’t supplying the pressure. Water pressure comes from the external source and passes through the hose, pressure regulator, filters, city-water inlet and RV plumbing before reaching the faucets.
That gives us a useful troubleshooting path.
Quick Summary
If your RV has low or no water pressure while connected to city water:
- Check the water pressure at the campground or household faucet.
- Make sure the fresh-water hose isn’t kinked or restricted.
- Bypass or test the pressure regulator.
- Check external and onboard water filters.
- Inspect the city-water inlet.
- Check the RV’s water-system valve positions.
- Determine whether every fixture or only one fixture is affected.
- Compare city-water operation with the onboard water pump.
Important: If the RV has good water pressure when using the onboard pump but poor pressure on city water, concentrate on the city-water supply side of the system.
If the water pump runs but won’t build pressure, see our Pump Runs But There’s No Water Pressure troubleshooting guide instead.
Safety Stop
Before disconnecting plumbing components, shut off the city-water supply and open a faucet to relieve pressure.
Water trapped in the plumbing may remain pressurized even after the outside faucet has been turned off.
If you’re working around electrical equipment, converters, wiring or appliances, keep water away from electrical connections.
Don’t exceed the RV manufacturer’s recommended water pressure when testing the system. Excessive pressure can damage RV plumbing and fittings.
Start Here: Does the RV Have Any City-Water Flow?
Open several fixtures:
- Kitchen faucet
- Bathroom faucet
- Shower
- Outside shower, if equipped
The pattern helps determine where the restriction is located.
No water from any fixture
Start at the external water source and work toward the RV.
The problem could be:
- Water source turned off
- No campground water pressure
- Kinked or blocked hose
- Faulty pressure regulator
- Plugged water filter
- City-water inlet problem
- Incorrect valve position
- Plumbing restriction
Weak water from every fixture
You probably have a restriction somewhere before the plumbing branches off to the individual fixtures.
Concentrate on the water source, hose, regulator, filters and city-water inlet first.
Only one fixture has low flow
The main city-water supply is probably working.
Check that individual fixture for a plugged aerator, shower head, faucet cartridge, supply line or local shutoff valve.
Step 1: Check the Water Source
Start outside the RV.
Disconnect the fresh-water hose from the RV.
Place the end somewhere the water can safely discharge and briefly turn on the campground or household faucet.
You should have a strong, steady flow of water.
Little or no water from the source
The problem may not be with the RV at all.
Check:
- Faucet fully open
- Campground water supply
- Household water supply
- Frozen plumbing in cold weather
- Restrictions or problems at the water connection
If the water source itself has poor pressure, the RV can’t improve it.
Strong flow from the source
Now you know the supply is capable of providing water.
Continue toward the RV.
Step 2: Check the Fresh-Water Hose
Inspect the entire hose.
Look for:
- Kinks
- Sharp bends
- Crushed sections
- Collapsed hose
- Damaged fittings
- Debris inside the connections
A hose can still pass water while restricting enough flow to make the RV’s water pressure seem poor.
Straighten any kinks and test again.
If you have another known-good drinking-water hose available, temporarily swapping hoses can be an easy diagnostic test.
Step 3: Check the Water Pressure Regulator
Many RV owners use a pressure regulator between the campground faucet and the RV.
That’s a good idea—but the regulator can also become a restriction.
A damaged, plugged or incorrectly adjusted regulator can dramatically reduce water flow.
If your regulator has a pressure gauge, check its reading while water is flowing.
If you have an adjustable regulator, verify that it is set according to the RV manufacturer’s recommendations.
Technician Tip
A pressure reading with every faucet closed doesn’t tell the whole story.
You can have acceptable static pressure but poor flow when a faucet is opened.
Watch what happens when water is actually being used.
If pressure drops dramatically as soon as a fixture opens, look for a restriction or inadequate supply upstream.
Step 4: Check the Water Filters
Water filters are a very common source of restricted city-water flow.
Your RV may have:
- An external inline hose filter
- A whole-RV filter
- An under-sink filter
- Multiple filters
A dirty filter may still pass water, but not enough to supply several fixtures normally.
If appropriate for your system, temporarily bypass the filter and test the water flow again.
Flow improves dramatically
You’ve probably found the restriction.
Replace or service the filter as recommended by its manufacturer.
Flow remains poor
Continue troubleshooting.
Step 5: Check the City-Water Inlet
The city-water inlet is more than just a fitting where the hose attaches.
Many RV city-water connections contain a check valve that prevents water from flowing backward out of the inlet when the onboard pump is being used.
If that valve sticks, becomes damaged or is obstructed by debris, city-water flow can be reduced or completely blocked.
With the water disconnected and pressure relieved, visually inspect the inlet for:
- Debris
- Damaged screens
- Mineral buildup
- Damaged fittings
- Obvious problems with the inlet
Don’t force or disassemble a check valve unless you’re familiar with its construction. Some inlet assemblies are easier and safer to replace than repair.
Step 6: Check the Water-System Valve Positions
Modern RVs can have surprisingly complicated water-management systems.
Depending on the RV, valves may select functions such as:
- City water
- Tank fill
- Normal operation
- Winterization
- Sanitizing
- Dry camping
If one or more valves are in the wrong position, city water may not flow normally through the plumbing.
This is particularly worth checking after:
- Winterization
- De-winterization
- Filling the fresh-water tank
- Servicing the plumbing
- Someone else operating the RV
Compare the valve positions with the diagram supplied by the RV manufacturer.
Don’t assume a valve is correct simply because it looks open—the plumbing arrangement varies considerably between RVs.
Step 7: Check Whether the Problem Is at One Fixture
If most faucets have good pressure but one doesn’t, stop troubleshooting the main city-water supply.
The problem is probably local to that fixture.
Faucet has low flow
Remove the faucet aerator and briefly test the faucet without it.
Inspect the aerator for:
- Sediment
- Mineral deposits
- Plastic shavings
- Small pieces of debris
Plugged faucet aerators are one of the most common causes of low flow I’ve encountered in RVs.
They’re also one of the cheapest problems to fix.
Shower has low flow
Inspect the shower head.
Mineral deposits and debris can restrict the small openings.
Some RV shower heads also contain flow restrictors that naturally limit the amount of water they deliver.
If every other fixture works normally, don’t start replacing pumps or tearing into the RV’s main plumbing.
Follow the symptom.
Step 8: Compare City Water With the RV Water Pump
This is one of the most useful diagnostic tests you can perform.
Disconnect the city-water supply.
Make sure there is sufficient water in the fresh-water tank.
Turn on the RV water pump and test the same fixtures again.
Good pressure with the pump, poor pressure on city water
Excellent diagnostic clue.
The downstream RV plumbing is capable of providing good flow.
Concentrate on:
- External water source
- Fresh-water hose
- Pressure regulator
- External water filter
- City-water inlet
- City-water-specific plumbing or valves
The onboard pump is unlikely to be the cause.
Poor pressure on both city water and the pump
Now look for something common to both systems.
Possible causes include:
- Plugged faucet aerators
- Plugged shower head
- Onboard water filter
- Partially closed plumbing valve
- Restricted plumbing
- Problems affecting individual fixtures
If only the pump has poor pressure, switch to the Pump Runs But There’s No Water Pressure guide.
This article is specifically for problems occurring while connected to city water.
Step 9: Check for Restrictions Inside the RV
If you’ve confirmed good water supply at the RV but still have poor flow throughout the system, there may be a restriction farther downstream.
Possible causes include:
- Kinked PEX or flexible tubing
- Partially closed valve
- Plugged fitting
- Debris in the plumbing
- Restricted water filter
- Damaged check valve
- Incorrect water-management valve position
Think about when the problem started.
If it appeared immediately after plumbing repairs, winterization, de-winterization or other service, inspect the areas that were recently disturbed first.
Common City-Water Symptoms and What They Suggest
| Symptom | Start by checking |
|---|---|
| No water anywhere | Water source, hose, regulator, inlet, valves |
| Weak water everywhere | Regulator, filter, hose, inlet |
| Good pump pressure, poor city-water pressure | City-water supply side |
| Poor pressure on pump and city water | Shared plumbing, filters or fixtures |
| One faucet has poor flow | Faucet aerator or local plumbing |
| Shower only has poor flow | Shower head or restrictor |
| Pressure starts strong then drops | Supply or upstream restriction |
| Problem started after winterizing | Valve positions and city-water inlet |
| Problem started after changing filter | Filter installation or restriction |
Most Common Causes of Low City-Water Pressure in an RV
In my experience, I’d start with the simple external components before assuming there’s a problem buried inside the RV.
Common causes include:
Low campground water pressure
The RV can only work with the pressure and flow supplied to it.
Kinked fresh-water hose
Especially easy to overlook when the hose is routed around the campsite.
Restricted pressure regulator
A regulator can create a bottleneck even when water is available at the source.
Plugged water filter
A dirty filter can substantially reduce flow.
City-water inlet restriction
A damaged or sticking check valve can interfere with incoming water.
Incorrect valve positions
Particularly after winterization or tank filling.
Plugged faucet aerators
Very common when the problem affects only one or two fixtures.
When to Book Service
Consider having the RV inspected if:
- You have confirmed strong water flow at the external source.
- The hose, regulator and external filters have been eliminated as possible causes.
- The city-water inlet appears damaged.
- Water flow remains poor throughout the RV.
- You suspect a hidden plumbing restriction.
- A water-management valve isn’t operating correctly.
- There is water leaking inside the RV.
- You’re uncomfortable disconnecting or inspecting plumbing components.
Before the appointment, tell the technician whether the problem occurs on city water, the onboard pump, or both.
That one piece of information can significantly narrow the diagnostic path.
Service Call Prep
Before contacting a technician, note:
- Whether the problem affects every fixture
- Whether the problem occurs only on city water
- Whether the onboard pump provides normal pressure
- Whether you’ve tried another hose
- Whether you’ve checked the regulator
- Whether you’ve bypassed or replaced the water filter
- Whether the RV was recently winterized or de-winterized
- Whether any plumbing work was recently performed
These details can save diagnostic time.
Why This Happens
City water and the onboard RV water pump ultimately feed much of the same plumbing, but they don’t supply that plumbing in the same way.
When you’re using the fresh-water tank, the RV’s 12-volt pump creates the water pressure.
When you’re connected to city water, the external water supply provides the pressure.
That means an RV can work perfectly from its onboard pump while having terrible water flow on city water.
The reverse can also happen.
That’s why comparing the two water sources is such a useful troubleshooting test.
Instead of guessing which component has failed, you’re using the RV’s plumbing arrangement to isolate which side of the system contains the problem.
Frequently Asked Questions
Why does my RV have good water pressure with the pump but not city water?
The problem is likely somewhere on the city-water side of the system. Check the external water source, hose, pressure regulator, filters, city-water inlet and related valves.
Can an RV water pressure regulator cause low water pressure?
Yes. A regulator that is restricted, damaged or incorrectly adjusted can reduce flow through the entire RV.
Can an RV water filter cause low pressure?
Absolutely. As a filter collects sediment and debris, it can increasingly restrict water flow.
Why does only one RV faucet have low water pressure?
If other fixtures work normally, check the affected faucet’s aerator, cartridge, supply line and local plumbing. A plugged aerator is a very common cause.
Should the RV water pump be on when connected to city water?
Normally, no. When connected to a functioning city-water supply, the external supply provides the pressure and the onboard pump isn’t required.
Why do I have no water from the city connection?
Start at the external source and work toward the RV. Verify water is available, then check the hose, regulator, filters, city-water inlet and water-system valve positions.
Related RV Water Troubleshooting
If your symptoms don’t match this article, the problem may belong to a different troubleshooting path:
Pump Runs But There’s No Water Pressure — use this when the onboard water pump runs but doesn’t successfully supply usable water pressure.
RV Water Pump Won’t Turn On — use this when the pump doesn’t run at all.
Written by Dan Harvickson (Founder of Last Mountain Tech) RV Specialist