An RV water pump is a 12 V demand pump that pushes water out of your fresh tank when you are not hooked to a hose. A pressure switch inside it starts the pump when you open a tap and stops it again when the lines reach the pump's shut-off pressure.
RV Water Pumps Explained: GPM, PSI, 12 V Draw and Choosing a Replacement
Some links on this site are affiliate links: if you buy through them we earn a commission, at no extra cost to you. As an Amazon Associate we earn from qualifying purchases.
At a glance
- What turns it on: not the tap, but a pressure switch that senses the line pressure dropping.
- What the numbers mean: the gallons-per-minute figure on the box is measured with nothing pushing back, so you get less at the shower; the shut-off pressure is just where the pump stops, not a sign of more water.
- Replacing one: match the ports, mounting and 12 V circuit, use the fuse printed on the pump label, and fit an inlet strainer.
On this page (7)
Our picks
- Shurflo Revolution 4008-101-E65 water pump, 3.0 GPM: by-pass pump, shuts off at 55 PSI; wants a 10 amp circuit
- Shurflo 4048-153-E75 High Flow water pump, 4.0 GPM: more flow for more outlets; 10 A draw, so check the circuit first
- Remco 55-Aquajet ARV variable speed water pump: 5.3 GPM, variable speed; may need heavier wiring than the pump it replaces
- Shurflo 182-200 accumulator tank: only if your pump cycles; pre-charge it to the pump's restart pressure
How your water pump works when you open a tap
The pump only runs while water is flowing, as long as it has water in the tank, its switch on at the monitor panel and enough 12 V power from the battery or converter. Remco puts it plainly: opening a faucet lowers line pressure and starts the pump, and closing it raises the pressure and turns the pump off. Jayco notes some cycling is normal.
Two pressures matter: the pump stops at its shut-off pressure and starts again at a lower re-start pressure. Shurflo's RV pumps shut off at 55 PSI and re-start at 40 PSI. Remco prints the OFF pressure on the pump label.
What GPM and PSI mean for you
The flow figure on the box is the best case, not what you get at the shower. GPM is gallons per minute, how much water the pump moves. PSI is pounds per square inch, how hard it pushes. The more pressure in the lines, the less water the pump moves and the more current it pulls.
The Shurflo Revolution 4008-101 data sheet shows this at 12 V. At 0 psi it moves 3.0 GPM on 2.2 A. At 40 psi, nearer the pressure your shower runs at, it moves 1.2 GPM and pulls 6.0 A.
Tip: Low voltage cuts flow too. Remco wants at least 11 volts measured at its 55AQUAJET-AES while it runs, and says to add a relay if you cannot get it.
RV water pumps by the numbers
Use this table to compare a replacement with the pump you have. Flow is each maker's zero-pressure figure.
| Model | Flow | Shut-off pressure | Max amps | Control |
|---|---|---|---|---|
| Shurflo Revolution 4008-101 | 3.0 GPM | 55 PSI (re-start 40) | 7.5 A | Pressure switch, internal by-pass |
| Shurflo 4048-153 High Flow | 4.0 GPM | 55 PSI (re-start 40) | 10 A | Pressure switch, internal by-pass |
| Remco 55AQUAJET-AES | 3.4 GPM | 65 PSI | 6.5 A | Variable speed |
| Remco 55AQUAJET-ARV | 5.3 GPM | 65 PSI | 10 A | Variable speed |
| Remco 53REBEL-JRV | 3.2 GPM | 55 PSI | 10 A | Pressure switch, by-pass |
| Remco 54REBEL-JRV | 4.0 GPM | 55 PSI | 13 A | Pressure switch, by-pass |
| Remco 55REBEL-JRV | 5.3 GPM | 55 PSI | 15 A | Pressure switch, by-pass |
| Flojet R3426504A | 1.4 GPM | 30 PSI | 2.2 A at 30 PSI | Pressure switch, internal by-pass |
Figures from Remco's Aquajet and Rebel sheets, Shurflo's sheets and RV catalog, and the Flojet R3426504A datasheet.
Pressure switch pumps, variable speed pumps and accumulators
The pump type decides whether it pulses at low flow and whether an accumulator helps. Most RV pumps, including Remco's Rebel series, are by-pass pumps: a pressure switch starts and stops the motor, and an internal by-pass valve lets water loop back at low flow, which Shurflo says gives steady flow with virtually no cycling. Remco's Aquajet uses a variable speed controller instead.
An accumulator tank is a small bladder vessel after the pump that stores water under pressure. Shurflo says it gives longer pump life, less noise and less pulsation with pressure switch pumps, and works best pre-charged to the pump's re-start pressure. Makers differ on whether you need one:
- Shurflo: its Revolution and High Flow by-pass pumps do not require one.
- Flojet: not with variable speed pumps.
- Forest River: fit one after the pump, or remove plumbing restrictions, if the pump cycles rapidly.
- Remco: the Aquajet uses a coil of flexible outlet tubing instead.
Tip: Leave the adjustment screws alone. Shurflo says by-pass adjustment is for a professional technician with proper gauges, and Remco says never to adjust the demand switch without consulting the factory. Over-adjusting can make the by-pass and the switch overlap so the pump never shuts off.
Choosing a replacement pump
A good replacement matches your old pump's flow, ports, mounting and electrical circuit. For sizing by fixtures, Flojet's rule of thumb is about 1 GPM per outlet. Count every outlet the pump feeds, including the outside shower and any appliance on the fresh line, such as a tankless water heater.
What has to match on the bench:
- Ports. Shurflo's RV pumps use 1/2 inch NPSM male ports, and Remco's Aquajet and Rebel use 3/4 inch quick attach female. The Flojet uses 12 mm quick connects.
- Mounting. Shurflo's 4008 mounts in any position within 6 feet of the tank. Flojet and Remco prefer theirs horizontal.
- Plumbing. Shurflo recommends at least 18 inches of flexible high pressure hose on both ports, not rigid PEX, and at least 1/2 inch inner diameter line. Small shut-off valves, elbows and winterizing valves cause low flow and noise.
- Strainer. All three makers require an inlet strainer between the tank and the pump: Shurflo specifies 50 mesh and Flojet 40 mesh, as a warranty condition. Remco warns that debris makes the internal valves stick open.
The electrical side is where an upgrade bites. Remco warns that its five chamber Aquajet pumps may draw more current than the pump they replace, so the fuse, wiring, switch and controller must all be sized for it, because undersized components may overheat and cause an electrical fire. Shurflo's 4008 wants a 10 amp circuit minimum, and a 7.5 amp Intellitec pump controller must be replaced or backed by a high current relay.
Use the fuse rating printed on your pump's label, from 5 A on the Flojet to 20 A on the largest Rebel. Running a new, heavier supply wire into the 12 V distribution panel is work for a qualified RV technician.
Tip: No pump maker publishes a decibel figure, so "quiet" claims cannot be compared. Most noise comes from rigid plumbing, which the flexible hose prevents.
Can you leave the water pump on?
Switch the pump off whenever you are not using water. Shurflo, Remco and Flojet all say so, Flojet because its pump is rated for intermittent duty only. Jayco says continuous or high pressure running shortens the pump's life and is not covered by warranty.
On city water the pump stays off, because the city water inlet is already pressurized and bypasses the tank. Forest River and Winnebago's 2026 towables manual both say not to switch the pump on while an external supply is connected.
Running dry is where makers split. Shurflo, Remco and Flojet say their pumps can run dry without damage, while Winnebago warns it can damage the pump and void the warranty, so keep the switch off when the tank is empty. If your pump short cycles, will not prime or runs with every tap closed, see water pump problems for the checks.
Common questions
What GPM water pump does an RV need?
For a factory-fitted pump, look up its OEM part number on Shurflo's conversion chart and buy the aftermarket number it lists, because OEM numbers are sold to coach builders only. The chart covers the older 2088, 4900 and 5900 series, so flow and pressure match without you choosing a figure.
Should I leave my RV water pump on all the time?
No. Flojet warns that a pump with an integrated pressure switch can start without warning whenever it senses pressure below the shut-off setting. Cutting power at the switch when you leave the RV prevents that.
Do I need an accumulator tank with my RV water pump?
Only if your pump cycles noticeably. Shurflo's example is a 45 psi pump that turns back on around 30 psi, and the tank holds that difference. If you fit one, check its pre-charge seasonally with an ordinary tire gauge, since temperature and altitude change it.
Can I use the water pump while hooked to city water?
No. Remco notes that with inlet water pressure present the pump will not stop forward flow even with the motor off, so the system needs a positive shut-off on the supply. Keystone also says to always fit a water pressure regulator and not to leave the RV connected and unattended for extended periods.