HQUA TWS-12
#5 in Up to 12 GPMFull review
A compact budget unit for a tight utility room, with cheap lamps. Like other budget units it tells you little about the dose.
Amazon $259.99$259.99
The HQUA TWS-12 is the better UV water purifier overall, rated 2.4 to 2.2. The HQUA TWS-12 costs $39.91 less ($259.99 vs $299.90).
iSpring UVF55FS
#9 in Up to 12 GPMFull review
A popular budget point of entry UV for a well that already has sediment filtration. Fine as a backstop, but nothing tells you the dose is being met.
Amazon $299.90$299.90
Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every up to 12 GPM UV water purifier; a clear win is highlighted. How we rank explains each one.
| Factor weight | HQUA TWS-12 | iSpring UVF55FS |
|---|---|---|
| Overall rating | 2.4/5 | 2.2/5 |
| Value 25% | 63 $54.16 per GPM ($259.99, 4.8 GPM at 40 mJ/cm², from 12 GPM at an unstated dose taken as 16) | 58 $62.48 per GPM ($299.90, 4.8 GPM at 40 mJ/cm², from 12 GPM at an unstated dose taken as 16) |
| Certification 20% | 0 not NSF/ANSI 55 certified, and no UV dose published | 0 not NSF/ANSI 55 certified, and no UV dose published |
| Monitoring 20% | 50 monitoring not published (neutral score used) | 30 lamp failure alarm |
| Lamp life 10% | 6 9,000 hour mercury lamp | 6 9,000 hour mercury lamp |
| Warranty 25% | 0 1-year warranty | 0 1-year warranty |
Specifications
| HQUA TWS-12 | iSpring UVF55FS | |
|---|---|---|
| Disinfection | ||
| Rated flow | 12 GPM | 12 GPM |
| NSF/ANSI 55 | No | No |
| Lamp | Mercury | Mercury |
| Lamp power | 55 W | 55 W |
| Lamp life | 9,000 hours | 9,000 hours |
| Monitoring | ||
| UV intensity sensor | - | No |
| Lamp failure alarm | - | Yes |
| Shutoff valve | - | No |
| Build | ||
| Chamber | - | 304 stainless steel |
| Ports | 0.8 in | 1 in |
| Maximum pressure | - | 85 psi |
| Voltage | 120 V | 120 V |
| Warranty | 1 year | 1 year |