Wassermann 3WDP4 4.0 GPM 45 psi
#7 in 4 GPM and upFull review
A low-cost 4 GPM pump for a trailer owner who wants more flow than the stock pump. Its sibling 5 GPM model costs only a few dollars more.
Amazon $59.99$59.99
The Wassermann 3WDP4 4.0 GPM 45 psi is the better RV water pump overall, rated 3.3 to 2.8. The Wassermann 3WDP4 4.0 GPM 45 psi leads on value. The Shurflo Aqua King II Premium 4.0 wins on features and pressure. The Wassermann 3WDP4 4.0 GPM 45 psi costs $176.34 less ($59.99 vs $236.33).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Shurflo Aqua King II Premium 4.0
#10 in 4 GPM and upFull review
A marine-grade 4 GPM pump for boats and larger RVs with several fixtures. It costs more than pumps with similar flow and pressure.
Amazon $236.33$236.33
Which should you buy?
- Choose the Wassermann 3WDP4 4.0 GPM 45 psi for value ($15 per GPM ($59.99, 4 GPM) vs $59.08 per GPM ($236.33, 4 GPM)).
- Choose the Shurflo Aqua King II Premium 4.0 for features (internal bypass, runs dry without damage, thermal protection, strainer included vs runs dry without damage, strainer included) and pressure (55 psi shut-off vs 45 psi shut-off).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 4 GPM and up RV water pump; a clear win is highlighted. How we rank explains each one.
| Factor weight | Wassermann 3WDP4 4.0 GPM 45 psi | Shurflo Aqua King II Premium 4.0 |
|---|---|---|
| Overall rating | 3.3/5 | 2.8/5 |
| Value 25% | 100 $15 per GPM ($59.99, 4 GPM) | 11 $59.08 per GPM ($236.33, 4 GPM) |
| Flow 20% | 50 4 GPM rated open flow | 50 4 GPM rated open flow |
| Pressure 15% | 43 45 psi shut-off | 71 55 psi shut-off |
| Efficiency 10% | 50 maximum current draw not published (neutral score used) | 43 0.40 GPM per amp (10 A max) |
| Features 15% | 30 runs dry without damage, strainer included | 65 internal bypass, runs dry without damage, thermal protection, strainer included |
| Warranty 15% | 0 warranty not published, scored as none | 0 warranty not published, scored as none |
Specifications
| Wassermann 3WDP4 4.0 GPM 45 psi | Shurflo Aqua King II Premium 4.0 | |
|---|---|---|
| Performance | ||
| Rated open flow | 4 GPM | 4 GPM |
| Shut-off pressure | 45 psi | 55 psi |
| Max current draw | - | 10 A |
| Price per GPM | $15 | $59.08 |
| Self-priming lift | - | 6 ft |
| Features | ||
| Control | Pressure switch | Pressure switch |
| Diaphragm chambers | - | 4 |
| Internal bypass | - | Yes |
| Runs dry | Yes | Yes |
| Thermal protection | - | Yes |
| Strainer included | Yes | Yes |