Every RV water pump gets a score from 0 to 100% built from six factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Pumps are grouped by rated open flow, under 4 GPM and 4 GPM and up, and use the same scale in both groups.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per GPM of rated open flow | 25% |
| Flow | rated open flow | 20% |
| Pressure | pressure switch shut-off | 15% |
| Efficiency | rated flow per amp of maximum current draw | 10% |
| Features | variable speed, internal bypass, run-dry safety, thermal protection and strainer | 15% |
| Warranty | warranty length | 15% |
Where the numbers come from
Flow, shut-off pressure, current draw, features and warranty come from the maker’s spec page or manual, or the maker’s own copy on a retail listing. Where the two disagree, the maker’s spec page or manual is used. Prices are checked at Amazon, and the lowest price at a store the page links to is used.
The factors
Value is the current price divided by the rated open flow, in dollars per GPM, on a log scale, so halving the price always counts the same. $70 per GPM scores zero and $15 per GPM full marks.
Flow is the maker’s rated open flow: 2 GPM scores zero and 6 GPM full marks.
Pressure is the pressure switch shut-off: 30 psi scores zero and 65 psi full marks. Where a maker gives a shut-off range, the low end is scored.
Efficiency is the rated flow divided by the maker’s maximum current draw at 12 V: 0.25 GPM per amp scores zero and 0.6 GPM per amp full marks. A pump that draws less for its flow is easier on the battery bank and the wiring. A fuse size or a draw measured at part load isn’t a maximum draw and isn’t scored.
Features is 35% for variable-speed control, 20% for an internal bypass, 20% for run-dry safety, 15% for thermal overload protection and 10% for an inlet strainer included in the box.
Warranty is the maker’s warranty: 1 year scores zero and 4 years full marks.
What isn’t scored
Diaphragm chamber count, self-priming lift, weight, noise and release date are listed where published but not scored. Few makers publish a noise rating for these pumps.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. This applies mainly to maximum current draw, which several makers leave out. Features never score neutral: a feature the maker doesn’t mention counts as absent. The exception is warranty: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero, the same as a one-year warranty, and is marked estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.