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
The Shurflo Aqua King II Premium 4.0 and the Johnson Pump Aqua Jet WPS 4.0 are evenly matched, rated 2.8 and 2.8. The Shurflo Aqua King II Premium 4.0 leads on features and pressure. The Johnson Pump Aqua Jet WPS 4.0 wins on value. The Johnson Pump Aqua Jet WPS 4.0 costs $51.24 less ($185.09 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.
Johnson Pump Aqua Jet WPS 4.0
#12 in 4 GPM and upFull 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 $185.09$185.09
Which should you buy?
- Choose the Shurflo Aqua King II Premium 4.0 for features (internal bypass, runs dry without damage, thermal protection, strainer included vs none of the listed features) and pressure (55 psi shut-off vs 41 psi shut-off).
- Choose the Johnson Pump Aqua Jet WPS 4.0 for value ($46.27 per GPM ($185.09, 4 GPM) vs $59.08 per GPM ($236.33, 4 GPM)).
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 | Shurflo Aqua King II Premium 4.0 | Johnson Pump Aqua Jet WPS 4.0 |
|---|---|---|
| Overall rating | 2.8/5 | 2.8/5 |
| Value 25% | 11 $59.08 per GPM ($236.33, 4 GPM) | 27 $46.27 per GPM ($185.09, 4 GPM) |
| Flow 20% | 50 4 GPM rated open flow | 50 4 GPM rated open flow |
| Pressure 15% | 71 55 psi shut-off | 31 41 psi shut-off |
| Efficiency 10% | 43 0.40 GPM per amp (10 A max) | 50 maximum current draw not published (neutral score used) |
| Features 15% | 65 internal bypass, runs dry without damage, thermal protection, strainer included | 0 none of the listed features |
| Warranty 15% | 0 warranty not published, scored as none | 67 3-year warranty |
Specifications
| Shurflo Aqua King II Premium 4.0 | Johnson Pump Aqua Jet WPS 4.0 | |
|---|---|---|
| Performance | ||
| Rated open flow | 4 GPM | 4 GPM |
| Shut-off pressure | 55 psi | 41 psi |
| Max current draw | 10 A | - |
| Price per GPM | $59.08 | $46.27 |
| Self-priming lift | 6 ft | - |
| Features | ||
| Control | Pressure switch | Pressure switch |
| Diaphragm chambers | 4 | - |
| Internal bypass | Yes | - |
| Runs dry | Yes | - |
| Thermal protection | Yes | - |
| Strainer included | Yes | - |
| Build | ||
| Weight | - | 4.5 lb |
| Warranty | - | 3 years |