Every gas water pump gets a score from 0 to 100% built from five 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 port size, up to 2 in and 3 in and up, and flow has its own scale for each group.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per gallon a minute of maximum flow | 30% |
| Flow | maximum flow | 15% |
| Head | how high it pushes water | 10% |
| Solids | the largest debris it passes without clogging | 15% |
| Warranty | warranty for home use | 30% |
Where the numbers come from
Flow, head, suction lift, solids size, engine and warranty come from the maker’s spec sheet, manual or product page. Prices are checked at Amazon, the maker’s own store and farm and equipment retailers, and the lowest is used.
The factors
Value is the current price divided by the maximum flow in gallons a minute, on a log scale, so halving the price per gpm always counts the same. $15 per gpm scores zero and $1.50 full marks, on the same scale for every port size.
Flow is the maker’s maximum flow. For 2 in pumps, 100 gpm scores zero and 220 gpm full marks; for 3 in and up, 200 and 400.
Head is the maker’s maximum total head, how high the pump lifts water: 60 ft scores zero and 120 ft full marks.
Solids is the largest debris the pump passes: 1/4 in scores zero and 1 1/2 in full marks.
Warranty is the warranty for home use: 1 year scores zero and 5 years full marks. When the engine and the pump have different warranties, the shorter one counts.
What isn’t scored
Suction lift, engine size, fuel tank, runtime and weight are listed but not scored. Independent flow tests are shown on the product page when there are any.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as 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.