UV Systems for Well Water: Class A, Sized to Your Pump, After the Filters

Class A or Class B: the label that matters

NSF/ANSI 55 has two classes, and they are not two quality levels of the same product. They are for two different waters.

NSF/ANSI 55 · Class A and Class B

	Class A	Class B
UV dose	At least 40 mJ/cm² at the alarm set point1,2	16 mJ/cm²1,3
Made for	Microbiologically contaminated water that is visually clear4	Water already deemed safe to drink; not for contaminated water3
Targets	Bacteria, viruses, Cryptosporidium and Giardia1	Normally occurring nuisance microorganisms3

Health Canada recommends Class A for well water treatment⁵. Some places require it: Ohio makes anything else illegal as primary disinfection for a private water system¹. Many units sold online carry no NSF class at all and quote the maker’s own dose instead³. If a unit has no Class A listing, it is not a fix for a well with bacteria.

UV needs clear water

The light has to reach every bacterium. Iron, manganese, hardness and cloudy water block it or coat the quartz sleeve around the lamp. Makers and health departments publish limits, and they mostly agree:

Water limits for UV · by source

Limit	VIQUA and LUMINOR	Nova Scotia	Ohio
Iron	under 0.3 ppm0.3 mg/L2,4	under 0.3 ppm0.3 mg/L6	treat at 0.3 ppm0.3 mg/L or more1
Manganese	under 0.05 ppm0.05 mg/L2,4	under 0.05 ppm0.05 mg/L6	not stated
Hardness	under 7 gpg120 mg/L2,4	under 7 gpg120 mg/L6	treat at 6 gpg103 mg/L or more1
Turbidity	under 1 NTU2,4	under 1 NTU6	pre-filter at 5 NTU or more1
UV transmittance	over 75%2,4	over 75%6	not stated

UV transmittance (UVT) is how much UV light passes through the water. VIQUA says a drilled well is typically at 85 to 97%, and a dug well or surface water at 55 to 80%⁷. Water that looks clear can still have low UVT⁸, so a dug well should get a UVT test before you buy.

The exception in our catalogue: the UV Pure Hallett 500PN accepts up to 3 ppm3 mg/L of iron and 50 gpg855 mg/L of hardness, because its sleeve is wiped clean automatically⁹.

Size it to your pump

VIQUA’s rule: the maximum flow your pump can deliver decides the model. Do not undersize, and when in doubt, take the next size up⁷. A typical whole-home unit runs from 5 to 18 gpm⁷; Penn State suggests at least 6 gpm for most single-family homes¹⁰.

Watch which flow the box quotes. The same chamber is rated for very different flows depending on the dose and water quality behind the number: one VIQUA model is rated 42 gpm at 16 mJ/cm² and 95% UVT, but 16 gpm at 40 mJ/cm²¹¹. For a well with bacteria, the only number that counts is the Class A flow on NSF’s listing¹².

Class A units with published limits

All four are certified Class A on NSF’s listing, made in Ontario and sold mainly through dealers. None has an Amazon listing we could confirm.

Class A UV, small to mid-size home

LUMINOR BlackComb 6.1 A (LB6-15XA)

NSF/ANSI 55 Class A

Class A flow

7.9 gpm · 29.9 L/min

Power

62 W

Lamp

9,000 h, replace yearly

UV sensor

standard

Water limits

iron < 0.3 mg/L, hardness < 7 gpg, UVT > 75%

Ports

1 in. MNPT

Strengths

• UV sensor included, with lamp reminders and alarm
• Low power draw
• 10-year warranty on the chamber

Drawbacks

• Lowest Class A flow of the four: check your pump
• Solenoid shut-off needs an optional module

Good fit: a single-family well with a pump at or under about 8 gpm and water already within the limits.
Skip it if: your pump delivers more than 7.9 gpm and you can't restrict it.

Class A UV, mid-size home

VIQUA PRO10

NSF/ANSI 55 Class A

Class A flow

10 gpm · 38 L/min

Power

120 W max

Lamp

about 18,000 h, replace every 2 years

UV sensor

standard, with flow meter and dose display

Water limits

iron < 0.3 mg/L, hardness < 7 gpg, UVT > 75%

Ports

1-1/4 in. MNPT / 1 in. FNPT

Strengths

• Shows the actual UV dose in real time
• Lamp change every 2 years instead of every year
• Bigger PRO20 (20 gpm, Class A) on the same platform

Drawbacks

• Higher power draw than the LUMINOR
• Solenoid valve is optional

Good fit: a single-family well with a pump up to 10 gpm.
Skip it if: your water exceeds the iron or hardness limit and you won't pre-treat it.

Class A UV, harder or iron-bearing water

UV Pure Hallett 500PN

NSF/ANSI 55 Class A

Class A flow

16.5 gpm · 62.5 L/min

Power

196 W, two lamps

Lamps

9,000 h, replace every 12 months

Sleeve

automatic wiper

Water limits

iron up to 3 mg/L, hardness up to 50 gpg, UVT 75%

Ports

1 in. MNPT

Strengths

• The widest water limits of the four
• Self-cleaning sleeve and two UV sensors
• Highest Class A flow here except the PRO20

Drawbacks

• Highest power draw
• Two lamps to replace each year
• Large wall-mounted unit (36.5 in.)

Good fit: a larger home, or water with some iron or hardness that you'd rather not pre-treat for the UV.
Skip it if: a small pump and clear, soft water: a smaller unit does the job with less power.

For more flow, the VIQUA PRO20 is listed Class A at 20 gpm¹².

Where it goes, and the pre-filter

UV goes last, so nothing downstream can add particles. Before it, VIQUA and LUMINOR call for a sediment filter of 5 microns^3,4; Nova Scotia says 10 microns or less⁶. Health Canada goes further and recommends a filter certified to NSF/ANSI 53 before the UV⁵.

1. Well pumpraw water
2. Sediment filter5 micron
3. Iron filterif over 0.3 mg/Lif needed
4. Softenerif over 7 gpgif needed
5. UV lightClass A

Cartridge housing for a 5-micron pre-filter

Pentair Pentek Big Blue 20 in. (150233)

No NSF/ANSI listing found

Cartridge

20 x 4.5 in., any micron rating

Flow

15 gpm; 1 psi drop when new

Max pressure

90 psi

Ports

1 in. FNPT

Strengths

• Takes standard Big Blue cartridges from many brands
• Very low pressure drop
• Pressure-relief button for cartridge changes

Drawbacks

• Housing only: cartridge, wrench and bracket sold separately
• Must be kept from freezing

Good fit: adding the 5-micron stage a UV maker asks for.
Skip it if: you want a flush-only screen with no cartridges to buy.

Upkeep

UV upkeep · what makers and agencies say

Task	How often
Replace the lamp	Every year for most lamps (about 9,000 hours)4,8; every 2 years for VIQUA PRO2. A lamp can still glow after losing much of its strength1
Clean the quartz sleeve	At least every 12 months, every 3 to 6 months with mineral-rich water7; every 6 to 12 months4; monthly6
Test the treated water for bacteria	Every three months6

A UV unit does nothing during a power failure unless it has a backup supply⁶. VIQUA and LUMINOR say to chlorinate the plumbing again after the unit has been off or out of service^3,4. Power use is low: VIQUA compares a typical whole-house unit to a 40-watt bulb⁷.

What UV does not do

• No residual. UV kills bacteria only inside the unit¹³. Bacteria already in your pipes stay there, so the plumbing must be chlorinated right after the UV is installed^3,14.
• No chemicals removed. Nitrate, arsenic, iron and hardness pass straight through.
• Not for heavy contamination. Penn State advises against UV when total coliforms exceed 1,000 or fecal coliforms 100 per 100 mL¹³.