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 rates 3.3 among 4 GPM and up RV water pumps; the Johnson Pump Aqua Jet WPS 3.5 rates 2.8 among under 4 GPM ones. The Wassermann 3WDP4 4.0 GPM 45 psi costs $77.50 less ($59.99 vs $137.49).
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.
Johnson Pump Aqua Jet WPS 3.5
#5 in Under 4 GPMFull review
A marine pressure pump with a 3-year warranty, for boats where 41 psi is plenty. RV owners after a firmer shower should look at 55 psi pumps.
Amazon $137.49$137.49
Scores side by side
These two sit in different flow classes (4 GPM and up and under 4 GPM), and each is scored against the reference points for its own class, so a rating says how well each does among its own flow peers. How we rank explains each factor.
| Factor weight | Wassermann 3WDP4 4.0 GPM 45 psi | Johnson Pump Aqua Jet WPS 3.5 |
|---|---|---|
| Overall rating | 3.3/5 | 2.8/5 |
| Value 25% | 100 $15 per GPM ($59.99, 4 GPM) | 38 $39.28 per GPM ($137.49, 3.5 GPM) |
| Flow 20% | 50 4 GPM rated open flow | 38 3.5 GPM rated open flow |
| Pressure 15% | 43 45 psi shut-off | 31 41 psi shut-off |
| Efficiency 10% | 50 maximum current draw not published (neutral score used) | 50 maximum current draw not published (neutral score used) |
| Features 15% | 30 runs dry without damage, strainer included | 0 none of the listed features |
| Warranty 15% | 0 warranty not published, scored as none | 67 3-year warranty |
Specifications
| Wassermann 3WDP4 4.0 GPM 45 psi | Johnson Pump Aqua Jet WPS 3.5 | |
|---|---|---|
| Performance | ||
| Rated open flow | 4 GPM | 3.5 GPM |
| Shut-off pressure | 45 psi | 41 psi |
| Price per GPM | $15 | $39.28 |
| Features | ||
| Control | Pressure switch | Pressure switch |
| Runs dry | Yes | - |
| Strainer included | Yes | - |
| Build | ||
| Weight | - | 4.5 lb |
| Warranty | - | 3 years |