RV water pump running with no pressure: what to check and what it costs

An RV water pump that runs but gives no pressure in Sebring is usually a cheap fix: a clogged strainer, a suction-side air leak, or a valve in the wrong position, in the $125 to $250 range. A pump that is actually failed is $250 to $500 to replace. Trip fee $75 to $150, and we find the real cause before quoting the pump.

Check this first (ten minutes)

1. Is there water in the fresh tank? Tank gauges on RVs lie, especially after a season of hard water on the sensors. Look, or fill it.
2. The winterizing valves. Most rigs have a valve that switches the pump’s suction between the fresh tank and a winterizing pickup, and a water heater bypass. Either one in the wrong position gives you a pump that runs and no water at the taps.
3. The strainer. On the suction side of the pump there is a clear plastic bowl with a screen inside. Unscrew it. Sediment, algae, and scale from a tank that sat full through a humid summer clog it. Clean it, and check the bowl for cracks, because a cracked bowl sucks air.
4. Suction fittings. Hand-tighten every fitting between the tank and the pump. Air pulled in on the suction side is the most common reason a pump runs without building pressure, and it makes no puddle, so nobody finds it.
5. Open the nearest tap and listen. Surging, spitting water: air in the line. Nothing: the pump is not moving water. Water from some taps and not others: a valve or a clogged aerator on the dry tap.
6. Close every tap and listen to the pump. Runs on, then stops, then stays stopped: normal. Cycles on every few seconds: a leak or a bad internal check valve.

What is usually wrong

Same figures as the pricing page, with labor at $125 to $190/hr inside those ranges.

Why pumps and lines fail here

The water in a lot of Highlands County parks and fish camps is hard well water, and a fresh tank that sits full from April to November in a rig in storage grows things. The first sign in November is a strainer bowl full of sediment and a slimy screen, which starves the pump. The second sign is a pump diaphragm that has been sitting in that water, stiff and weak. Draining the tank and running the pump dry for a few seconds before leaving for the summer, then sanitizing the system on arrival, prevents most of it.

The other Florida failure is heat and vibration on plastic fittings. The pump lives in a cabinet that sits at the ambient temperature of a closed rig in July, well above the outside 91°F, for months. Plastic compression fittings relax, the pump’s own mounting feet dry out, and the vibration of the pump against a fitting that has relaxed is how a suction leak starts. A pump that was fine in April and sucking air in November did not fail; its fittings did.

Low pedestal pressure at the older parks and the 30-amp fish camps on Lake Istokpoga is a separate complaint. A rig on city water with weak pressure at every tap usually has a clogged inlet screen or a regulator that has failed closed, not a park problem. Both are $30 parts.

What the repair involves

We start on the suction side, because that is where most of these end: tank level, valve positions, strainer, fittings. Then the pump itself, metered under load. Then the pressure side for leaks, including the water heater relief valve and the toilet valve, which are the two hidden leaks on most rigs. A pump replacement, when it is needed, is a one-visit job from the truck on the common 12V demand pumps, and we set the new pump on fresh mounts with the fittings supported so the vibration does not start the next leak.

When to call

Now if you have no water and are living in the rig. In November on arrival if the rig sat through the summer, because a slimy strainer is on the arrival checklist for a reason. We do these on site across Sebring, Avon Park, Lake Placid, and the Lorida fish camps, and the plumbing and water heater page covers the rest of the system, tanks and valves included.