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Ultraviolet Sterilizers for Well Water

Welcome to Episode 10 of Clean Water Made Easy Podcast.

UV Sterilization for Well WaterOur host and resource person, Gerry Bulfin, a water treatment contractor and WQA Certified Master Water Specialist discusses ultraviolet sterilizers for well water and how to use them for disinfecting and sanitizing well water.

Ultraviolet sterilizers use UV light to kill bacteria in water and are often a good fit for you if your well or spring water has bacteria in it, or might be at risk for coliform bacteria.

Ultraviolet Sterilizers for Well Water

You will hear and learn about:

  • How does UV light disinfect (kill bacteria) in water?
  • How can I know if UV disinfection is right for my water application?
  • What is the difference between Class A and Class B UV sterilizers, and when to use which for a given application
  • Should the water be treated prior to UV sterilization?
  • Is UV light effective at killing parasites, such as Giardia?
  • Maintenance and servicing UV sterilizers


The Practical Guide to Ultraviolet Sterilizers



 Clean Water Made Easy Podcast Episode #10.

Ultraviolet Sterilizers for Well Water

Hello! Hope your day is going good. My name is Gerry Bulfin. I’m a water treatment contractor and WQA-Certified Master Water Specialist here in Northern California and I want to welcome you to the podcast. If it’s your first time, thanks for listening or welcome back if you’ve listened before. I really appreciated all the feedback and emails about the podcast I’ve been getting and if you have any questions or if you have any topics you would like to see covered on the podcast, please write me an email.

I like to say you’re in the right place if you want to learn about well water, water treatment systems or how to improve the quality of your well water or spring water as well.

In this episode, I am going to talk about Ultraviolet Sterilizers, a very popular device, and there are many different kinds.

Topics we’re going to go over are: How does it work? How does UV light disinfect to kill bacteria in the water? How can I know if UV is right for my particular application?

We are going to talk about the difference between Class A and Class B UV sterilizers and when to use which. Should the water be treated prior to UV? We are also going to talk about parasites such as Giardia and how to and how often to service UV sterilizers.

Download Free Guide

I’ve put together a guide on UVs called The Practical Guide to Ultraviolet Sterilizers and you can get your free copy. It has a lot of good pictures, diagrams and checklists. It is very easy to follow and pretty useful.

Bacteria can be really a serious issue. Harmful bacteria can be present in many water supplies. Proper disinfection as we all know is very critical, especially if bacteria, viruses and parasites are present.

Many well and spring waters are susceptible to contamination by bacteria. Most properly built wells usually do not have bacteria or are not under the influence of surface water where bacteria live but it can happen. So, you want to do routine testing at least once a year for coliform bacteria. It is recommended for home water wells.

Both the EPA, CDC, World Health Organization and different organizations like the National Ground Water Associations, all recommend that you get your water tested every year for coliforms. Ultraviolet sterilizers can be a good alternative method of disinfection.

Chlorine, is the most common type of disinfection to use especially for spring water. It can have limitations and there is some associated health risks especially if the chlorine residuals are high and you’re showering in it and breathing in chlorine. So you will look for alternatives for that and particularly if you have a home system and you want to be sure your well is free of bacteria. Often UV can be a really good way to go because it doesn’t have any chemicals and it’s effective under the right conditions.

How UVs Work

So how do UVs work? Well UVs sterilizers work basically by exposing the cell walls of bacteria of the organisms to intense ultralight. This disrupts the genetic material and then prevents the organism from reproducing.  So it’s kind of like the bacteria is getting a bad sunburn and they are not going to grow. Ultraviolet light is split in several different ranges UVA, UVB, UVC.

The UVB range would cause sunburn on humans. Water purifiers use the UVC range because of its germicidal abilities that can kill bacteria. In this range, the light will break molecular bonds of the DNA and basically it makes them unable to reproduce and effectively kills them. So, UV effectively destroys bacteria and viruses but it’s limited by the clarity of the water and that’s what we are going to talk about.

Essentially you have to have very clean water for it to work well. Otherwise the UV can’t shine into the water properly and get all the bacteria. Another consideration is, unlike chlorine, there is no downstream residual disinfection. So, you are killing the bacteria as it flows through, but if there’s something going on with your system where it’s introducing bacteria afterwards, then it won’t work.

The other thing that we are going to talk about is pre-treatment for iron, sediment, excessive hardness, and minerals. Again, the clarity of water to allow sufficient transmission of the UV light is important. Some people do get a  UV sterilizer for city water where they have bacteria.  In the U.S., it’s generally one of the safest public drinking water supplies in the world.

It’s highly regulated and there are professionals testing it but it can happen where you get bacteria or parasites. While it’s rare, if you’re in a situation where you have someone in your home with a compromised immune system, maybe they’re elderly or they recently had cancer or there’s something where their immune system is down, then they’re more susceptible to bacteria and parasites such as cryptospedium. Then people that might be exposed, might feel a little sick, but don’t even know what hit them, next day they’re fine.

There are some folks that do get UV sterilizers on city water just to be safe. So, that is something but what we mostly deal with is folks on well water and spring water. They use UV either as a final stage or maybe a secondary barrier after initial disinfection with chlorine or ozone. They use this as a final stage to make sure; or they use it as a primary means of disinfection.

Advantages of using UV sterilizer

What are the advantages of UV sterilizers? Well, I guess that they are very effective. If they’re set up and sized correctly, virtually all the micro-organisms will be susceptible and will be killed. They’re economical. You get hundreds of gallons of water for low operating cost.

Essentially, the operating cost will be a little bit of electricity and then you have usually change the UV lamp once a year, some go longer. They’re safe, there is no danger of overdosing, no addition of chemicals, they're fast fast, and water flows right through. That’s it.

The water is disinfected. They’re easy to set up. Again, as long as the conditions are correct. Also, they’re fully automatic, and that’s how you want the UV set up. You don’t want to have to turn it on and off. You want to make sure it’s either automatically turns on or most folks just leave it on all the time.

Factors affecting  UV Treatment

So what are the factors that affect UV treatment? Well, water treated by UV should be clear and relatively low in minerals. We generally like to see water that’s less than say 7 grains per gallon or less than about a 120 parts per million of hardness, really soft water is good or fairly soft water. The water should be free of color.

Really, it should have no iron or manganese in it, but different UV manufacturer say well if it’s less than 0.3 mg per liter of iron and less than 0.05 mg per liter of manganese, it should work okay. It's better to have very low, or no manganese and iron in the water. The ideal pH range is 6.5 to 9.5. Turbidity, which is how clear the water is or how murky it is, should be less than 1 mtu and so often, the UV sterilizers have some kind of pre-filtration.

Not always, like if your water is really good, but usually there is some type of pre-filter. If your water is already soft and free of iron and manganese, then often a simple 5 micron pre-filter, is installed prior to the UV. If you want a guarantee that it is going to be removing the parasites such as Giardia Cryptospernium, then you also want to have a 1 micron absolute filter that would remove the parasites. If you have a very high dosage, certain UV lights will actually inactivate Cryptospernium and Giardia, but generally to be safe, they recommend having a filter as well.

So the UV dosage is very important. This is generally when you buy the system that is already sized for you but I’m going to talk a little bit about Class A versus Class B. To kill bacteria, you want a certain amount of intensity of the UV rays at a certain wave length per cubic centimeter of water. I won't get too technical, but just know there is this thing called NSF. Different water devices are certified for NSF and there’s different classes that they certify,  there is a class A and a class B.

Differences between Class A and Class B UV Systems

Class A systems have a very high dose of UV so that it can kill pathogenic micro-organisms. And then Class B systems generally have a lesser dose and don’t have some of the fail-safes that Class A have. So that’s the main difference.

Class A systems are quite a bit more expensive and they usually have an alarm or some kind of a fail-safe. So if the water starts to have turbidity in it, or something builds up on the quartz sleeve that the UV light is shining through and the intensity is not able to reach the chamber correctly, then the system will shut off your water which will protect you.

There is also a flow control that are rated at certain flows. Like for instance, say your water is flowing at 10 gallons per minute, this is a size for homes, or small businesses, so 10, 15, or 20 gallons per minute is typical flow rates down to 4 or 5 gallons a minute. So in other words, each size UV, they all come in different sizes, and so they all often have a flow control which fixes your flow. So if you try to get more flow through there and then over power the UV so the water flows through the UV faster than the light can kill the bacteria, it will prevent that.

So, the Class A systems generally can be used on well and surface waters. They have that the higher dosage, or higher intensity, which is 40 million joules per cubic centimeter, which is the rating for the class A. Whereas Class B systems, they are generally used because they're a lot cheaper.  They are very effective but they are better for water that is safe from e-coli as serious contamination. For example, municipal water.

Again, if you know you’re not going to be exposed to microorganisms that could hurt you and if you know the waters are already treated, then you can get the Class B system. A UV sensor, which measures the intensity of the light, is required on a Class A system, and it is not required on a Class B system. On the Class A system there is a visual, audible alarm that is hooked up to a motorized valve that will shut off your water. Class B systems don't require that. Generally, on both Class A and Class B systems, there is a flow control required. The recommended gallons per minute is important.

Where to put the UV

One question that comes up is: Where do I put the UV?    If it’s for your home or business, you want it to be the last in line. So if you have a water softener or filter, you generally put it at the last so that the water is the clearest and the cleanest when it reaches the UV. Remember that the UV sterilizer don't offer downstream protection so generally you put it at the house.

For example, here in Northern California, a lot of folks have storage tanks, big holding tanks where the water is not pressurized. It is just sitting in holding tanks and being stored. Sometimes folks put a UV going into the storage tank so all the bacteria is killed in the water going into the storage tank. Well, you could do that but the water is prone to recontamination in the tank. You’re still better off having another UV sterilizer at the house. You want to make sure that the UV is the last in line.

The other thing to consider in UV is still do routine water testing. You still want to test for bacteria. There are home test kits available now that are particularly for this kind of thing. It’s not like a certified test that you could take to the bank or give to the government if they’re inquiring.  It gives you an idea like “I got bacteria here” or “Now I don’t have bacteria there.”   It’s fairly low-cost.

We want to talk again about Giardia.  Cryptosperdium and Giardia, they’re protozoans and compared to a bacteria, they're much larger.  Whereas it would be difficult to filter out a bacteria, unless you use a RO membrane or a ultra-filtration membrane, but generally for a whole house filter, they’re not gonna filter out bacteria. But you can filter out parasites such as cryptospernium and giardia.

Usually an absolute 1 micron filter will remove it. In fact, there had been quite a few cryptospernium outbreaks around the world, including U.S, and Canada. Again if folks have a compromised immune system, those are the people that are affected the most. This can result in death or the so-called stomach flu. Some folks that are elderly or sick can be more affected by it. This is common on city water or if your well is under the influence of surface water. So if your well is shallow or there’s water pouring into it from the surface somehow, you can be at risk for these parasites. A combination of a 1 micron absolute filter and UV is a very effective method for removing these bacteria.

What type should I choose?

Use the Class A. There are different brands available that are more expensive and if money is not an issue, that’s the better way to go. You got a failsafe system, you know when it's working. You’ve got a UV sensor.

If you think the water is safe, or you’ve tested it and it’s safe, but you just want to make sure that you get any bacteria that might be present, then you can use the Class B systems.

For residential application it’s important to know the size of your incoming pipe. So like for instance, if you have 1-inch pipe and you have a large home or say you have like a big family, four bathrooms, or maybe you’ve got a home and a guest home, then you don’t want to get a system that restricts that flow. So you want to size, as is the case with all water treatment equipment, you want to size your UV sterilizer for your application.

So different sizes, say you have a 1 bathroom home and there’s 1 or 2 persons in the home, a 6 gallon per minute UV sterilizer would work well. Say you have 1 to 2 bathrooms but you have 2 to 4 people in the home, generally a 10 to 12 gallon a minute would work well. That means for every minute that the water is flowing, 12 gallons will have passed through or 10 gallons have passed through. So that’s the flowrate in gallons per minute.

Sometimes in larger homes, say 3 to 4 bathrooms, 4 to 8 persons, or a multiple home situation where you’ve got a home and then a guest home, and you want 1 UV sterilizer, then that can get up in the 20 to 25 gallon per minute. So those are some common sizes that are available. Basically UV sterilizers are pretty easy to deal once you’ve set them up, most folks leave them plugged in all the time. The lights lit and when any water flows through there, everything is killed.

Maintenance & Servicing

If you have a situation where you want to prolong the life of the lamp and you were not there for long stretches of time, you can have it set up so that you have a timer and there’s a delay.  It takes several minutes after the UV is turned on to warm up.  That is available. You can have a situation where you flip on a switch and then there’s no water, then 3 minutes later you have water available.

You can shut them off, like I said, but most folks just leave it running day and night. If you leave it running 24 hours a day,  then it’s good for about a little over a year. It’s about 9000 hours. Generally, what we do is recommend to folks to change the UV light once a year.

A lot of folks would say “Hey, the lights didn’t burn out, it is still working” Well, true but what happens is that the glass itself can become solarized. It becomes less effective. It compromises how effective it can be at different flow rates. It won't be working at its optimum. If you gonna go through all the trouble doing it, do what is recommended and just change the lamp once a year.

Often, if you want it super clean, usually we recommend taking out the quartz sleeve and cleaning it. You can wipe it with alcohol or a mild non-abrasive detergent. Generally, just wiping it with some pure water and it if  is stained then that tells you something right there, that the pre-treatment is not good. You can rinse it with citric acid or vinegar if you have hard water stains on it. Anything that builds up on that quartz sleeve is going to suck the transmission of the UV light. You can see pictures of this on the website and on the guide.There’s an illustration and a cut away of it.

Essentially, a UV light is a slender stainless steel chamber and inside it is a quartz glass. It’s just a cylinder of glass. The lamp, the fluorescent light bulb, goes inside it and it is protected from exposure to the water.  It will shine in the water and kill the bacteria.

We’ve had very good success with UV lights. Many people have them for years in their homes, get the water tested, came back good for bacteria, even if they had problem with bacteria before that. We’ve had pretty good feedback on the. The biggest problem is if you don;t maintain them. That’s the biggest problem.

Okay that basically covers the basics of UV sterilizers. If you’d like to see some pictures and see that guide, it’s on the website at cleanwaterstore.com/blog/podcast. This is episode 10.

If you like what you’re hearing here, and use iTunes,  it’d be awesome if you can subscribe to get regular updates and give us a good rating and review. That would be extremely helpful.  If you have any questions, shoot me an email at [email protected].

I’m happy to help you with any question you have about UV sterilizer or anything in general questions about well water.  Have a good week. Thanks for listening.


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