Q&A about UV Water Purification Systems.

This article series explains procedures & reasons for using permanently-installed UV light (ultra violet light) treatment systems to address bacterial contamination in drinking water or well water - one of the options for correcting unsanitary or unsatisfactory drinking water.

UV - Ultraviolet light as a Water Purifier FAQs

These questions & answers about UV water treatment systems used to disinfect drinking water were posted originally

at UV ULTRAVIOLET LIGHT WATER TREATMENT - be sure to review that information.

 

How long was water remain "disinfected" and safe after UV Treatment?

Our house has a large tank in the loft (about 40 galls ) that feeds everything, this tank is fed by a pressurised system that goes through a UV filter;

can we say how long this water remains safe to drink, the family only come down two or three times a year? On 2021-06-26 by Don Chester

Answer by inspectapedia.com.moderator (mod)

@Don Chester,

Even with "new" water entering your tank (from a source you've not named) and even though you're treating it with a UV (light - not a "filter),

I would NOT assume that the water storage you described is now nor remains free of contaminants, including bacteria; it'd make sense to include a disinfection system, including one like those described at WATER TREATMENT EQUIPMENT CHOICES - home

Where to buy a 12C or 24VDC Water Disinfectant Light System?

We get our water supply from the fellside via a break tank.we are considering putting in a solar panel system for an electric supply which will be 12or 24 volts,

is it possible to run a u.v. System to treat our incoming water supply on either of these voltages. On 2021-05-14 by Michael.

Answer by danjoefriedman (mod) - where to buy 12V and 24VDC UV water treatment disinfectant light systems

@Michael.,

Thank you for asking a helpful question about the availability of 12V and 24VDC UV water treatment disinfectant light systems.

Certainly, you can find both 12V and 24V UV water treatment equipment from quite a few manufacturers. Below I paste in an example showing UV lights from MiniPure, MIghtyPure, and Sanitron. (There are others)

I clipped this shot from a third party vendor, https://purestfilters.com/, who distributes UV treatment systems from a slew of sources.

(to be clear: InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website. )

Contaminants in swimming pool water interfere with UV disinfection

What might be in my pool water that would drop its transmittanve to 93 percent as it passes through the UV filter chamber?

Do phosphates block UV light from penetrating through the water column? On 2020-07-11 by Aaron Bond

Comments by danjoefriedman (mod)

Aaron

In general, any suspended particles or contaminants (such as iron) that cloud the water so as block or diffuse or refract light can interfere with UV treatment.

Phosphates, if over 100 ppb, can encourage algal growth that in turn can cloud the water.

Cost to install a UV system for home water chemical contamination?

How much does it cost to install an uv system for a 4 bedroom house, 41 years old,

water constantly being compromised from round up, prodiamine, glyphosate, ethyl cyanide, lawn service products to keep up appearances where human/animal life is at risk.

Having all this contamination would an ultraviolet light be a good remedy? On 2020-05-29 by Carol

Answer by danjoefriedman (mod) - cost to install an uv system to get rid of chemical contaminants?

Carol

A UV system will have no useful effect on chemical contaminants in water.

You will need to install a water treatment system specifically designed to remove chemical contaminants, such as reverse osmosis combined with charcoal filtration.

How to determine if the UV light tube is burned out?

Do uv lamps lite up the full length of the tube? Mine does not. Just on the ends. On 2018-04-24 by Larry

Answer by danjoefriedman (mod)

Yes, for the ones that I have seen. I suspect your bulb is burned out. Of Course it also makes sense to check with the manufacturer.

Do I need to disinfect the hot water tank?

Do you need to let the bleach enter hot water tank as well or not? On 2018-03-10 by Mike

Explanation by (mod) -

Mike

Here we are talking about using a UV light to treat water for bacterial contamination. That treatment takes place ahead of ALL other water equipment, including your water heater.

However a water heater can develop its own bacterial contamination.

See WATER HEATER CAUSES of WATER ODORS https://inspectapedia.com/water/Sulphur_Odor_in_Water.php#Water_Heater

See WATER TREATMENT EQUIPMENT DISINFECTION - https://inspectapedia.com/water/Water_Equipment_Disinfection.php - how to disinfect water filters, water heaters, water tanks, activated charcoal systems, water softeners, sulphur treatment & other water treatment equipment.

Also see DRAIN a WATER HEATER TANK - https://inspectapedia.com/plumbing/Hot_Water_Tank_Drain_Procedure.php - for advice on how to flush the water heater.

Are otters contaminating water we draw from a freshwater bay?

we have a UV20 system. Sediment filter, charcoal filter then the UV bulb. We also have a pre filter that we change monthly. We draw our water from Georgian Bay but we are in a small sheltered Bay on Georgian Bay.

We were away for 10 days and I've been told if they are left stagnant for a period of time, it can get contaminated.

We also know that there were Otters in our Bay while we were away.We now have coliform and e coli. We just installed the new bulb in July. We have changed the pre filter, 1st and 2nd filter as required.

Can we now just change the pre 1st and 2nd and bleach the system without having to put a new expensive bulb in ? On 2017-10-03 by bev

Answer by (mod) - otters in the Georgian bay not a source of contamination

Bev
Otters in the Georgian bay would not alone be a significant cause of a coliform problem in your water. More-likely the system needs disinfection and filter replacement.

As long as there's no sign that the bulb has burned out, you do not need to replace a UV bulb based on coliform if it is a year old or less.

You'd replace a UV bulb if it were burned-out or if it has aged beyond the manufacturers' recommended usage-life.

 

What to do if a filter and UV don't correct unsanitary drinking water

What can I possibly do if my well water fails the coliform test after I've had a 5 micron filter and a UV light tube installed? On 2016-07-13 by Fern Perry

Moderator reply:

Fern:

Start with a bacteria test that gives a count so that you know the actual level of coliform contamination in your water supply. If the count is quite high then it's not likely that any UV light will be sufficient.

Instead, if you cannot find and fix the source of contamination in your well, you probably need a combination of filtration, chlorination, and possibly also UV.

What happens to water disinfection if the UV light is OFF?

If our UV water disinfection lamp is turned off does it affect or treat our drinking water? On 2016-05-09 by THAN On 2016-05-09 by THAN

Answer by (mod) -

Than

If your water system needs a UV light - typically to try to kill off bacteria in the water supply - and if the UV light is OFF - then the water is not safe to drink.

You can solve this problem temporarily by boiling all drinking water until the UV light is fixed. Beware that there are other limitations to the effectiveness of a UV light system and other maintenance required for the light to work properly - discussed in the article above.

Also search InspectrApedia.com for EMERGENCY DRINKING WATER to see other ways you can obtain safe drinking water until your UV system is repaired.

UV light on a water system doesn't affect water flow

Did uv light cause water level decreased fast? On 2016-04-13 by Anonymous

Answer by (mod) -

Anon a UV light on a water system doesn't affect water flow - it just shines light on water passing by.

Of course if sludge or mud or debris has collected anywhere in your piping system , including in the light, then not only might the water flow rate diminish, but the UV light will no longer be reliably treating the water.

Will a UV light remove iron bacteria from my well water?

Will UV solve the iron bacteria in my well water? On 2015-12-07 by Dianne

Answer by (mod) -

No, Dianne.

Will UV light remove or affect minerals in the water supply?

Query the UV light can affect or ruin the minerals of spring water? On 2015-10-12 by Anonymous

Answer by mod: no

No, UV disinfection only affects living organisms such as bacteria; it won't affect minerals in the water supply.

Chlorine + UV disinfection for shipboard drinking water - water smells like glue

Hello, I work on a ship and we use chlorine to dose our potable water tanks. We have a UV sterilizer as the last stop before the water goes to the accommodations for consumption. My question is, the shipyard put the rehardeners (we have reverse osmosis water makers) directly before the UV sterilizer.

The rehardener is a dolomite mixture. When we run the UV sterilizer the water that comes out of the taps almost has a glue like smell to it. We have confirmed that the smell of the water is related to the UV sterilizer being in operation.

Do you know if it is the rehardeners being located right before it goes into the UV as the issue? Have you ever heard of this before? Thank you On 2015-10-03 by Nicholas

...

Hello, we have the same issue (water has a glue like smell when the sterilizer is running) on a ship, and the crew reported that after switching off one of the two UV lamps of the sterilizer the smell is gone. Is there a logical explanation for this? On 2015-10-19 by Dino

Does the lack of heat in my cold water mean the UV disinfection light isn't working?

I have installed a new UV light. Noticed that the water out of cold water tap doesn't get hot when first water is used in the morning. Does this mean the bulb may be defective? If it is defective why doesn't the alarm go off? On 2015-09-24 by George Borovan

Answer by (mod) - No

No, George, the UV light does not impart significant heat to water flowing through the system.

Why would water out of the cold water tap get hot anyway?

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Continue reading at UV ULTRAVIOLET LIGHT WATER TREATMENT or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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• WATER QUALITY & QUANTITY San Miguel de Allende
• WATER TREATMENT EQUIPMENT DISINFECTION
• WATER TREATMENT EQUIPMENT CHOICES - home

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