Bacteria, E. coli & Giardia in Well Water: UV Disinfection

Coliform, E. coli and Giardia: what each one means

• Total coliform is an indicator, not usually harmful by itself. The EPA describes coliforms as bacteria that are naturally present in the environment and are used as an indicator that other, potentially harmful, bacteria may be present [EPA standard health effects language for drinking water (40 CFR 141, Subpart Q, Appendix B)]. The CDC explains that coliform bacteria generally won’t make you sick themselves, but they typically get into water the same way as germs that do [CDC: Guidelines for testing well water].
• E. coli points to fecal contamination and can make people sick. In the EPA’s words, its presence indicates that the water may be contaminated with human or animal wastes, and microbes in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms [EPA standard health effects language for drinking water (40 CFR 141, Subpart Q, Appendix B)]. The EPA adds that they may pose a special health risk for infants, young children, some of the elderly, and people with severely compromised immune systems [EPA standard health effects language for drinking water (40 CFR 141, Subpart Q, Appendix B)].
• Giardia is a parasite, not a bacterium. It travels in water as tough, microscopic cysts and causes an intestinal illness called giardiasis. The CDC notes that Giardia parasites can make you sick if you swallow them [CDC: About choosing home water filters].

Signs of bacteria and parasites

Usually none you can notice in the glass. That’s why a bacteria lab test comes first: it confirms the problem up front. The CDC recommends testing private wells for total coliform bacteria at least once a year [CDC: Guidelines for testing well water].

How we fix it

1. Bacteria lab test to confirm the problem. This step is required. Your county environmental health office or a state-certified lab handles bacteriological testing, and we’ll help you set it up. The result tells us what’s there: coliform, E. coli or Giardia.
2. Free in-home water test and consultation. Once the lab confirms bacteria, the next step is treatment. We come to you, look at how your well water enters the house, and check the things that decide how the UV system is sized and set up: flow, clarity, sediment, iron, manganese and hardness.
3. Sediment filter, then softener, then UV, installed. We usually recommend this order. The sediment filter and softener protect the UV, and the UV is sized to your home’s flow rate so every gallon is treated. Systems are built with NSF-certified components.
4. An honest look at the well. If we see signs of a damaged seal, cap or casing, we’ll tell you so a licensed well contractor can fix it. UV treats the water; it doesn’t repair the well.

Sediment filter, softener, then UV: why this order

UV (ultraviolet) disinfection treats the water passing through it, continuously, every time you use water, without adding chemicals or changing the taste. A properly sized UV system inactivates bacteria such as E. coli and parasites such as Giardia.

UV only works when the light can reach the water. The CDC notes that UV light does not work well in cloudy water because small particles can block germs from the light [CDC: How to make water safe in an emergency]. That’s why we usually recommend two steps ahead of the UV:

• Sediment filter first. It catches sand, silt and grit so the water reaching the UV is clear. See sediment.
• Softener second. Hardness minerals build up scale on the UV lamp’s quartz sleeve, which blocks the light over time. A water softener keeps the sleeve clean so the UV keeps working.
• UV last, so it treats clear, soft water right before it goes to your taps.

If your test also shows iron or manganese, we’ll account for it in the setup. See iron & manganese.

UV treats the water, not the well. A well with a structural problem, like a damaged seal or casing, may still need repair from a licensed well contractor. UV doesn’t replace that repair. We don’t sell or service well pumps, but we’ll tell you honestly when the well itself needs attention.

Why UV, not chlorine

We don’t do shock chlorination; we go with UV. Some well contractors shock chlorinate a well as a short-term step, but it’s a one-time treatment, and the Connecticut Department of Public Health notes that chlorinating a well is not always a permanent solution, as the bacteria may return [Connecticut Dept. of Public Health: Hydrogen sulfide in private wells]. Chlorine is also a weaker choice for Giardia: the CDC notes that disinfectants do not work as well as boiling for killing some germs, including the parasites Cryptosporidium and Giardia [CDC: How to make water safe in an emergency]. UV keeps working every day, which is why it’s our long-term fix.

Until treatment is in

If your lab test found E. coli or Giardia, use bottled or boiled water for drinking, cooking, brushing teeth and making ice until your UV system is installed. Call us and we’ll get your free in-home water test on the calendar quickly.

What UV gives you

• Peace of mind with every glass, with continuous treatment of every gallon entering your home.
• A protected family, with treated water at every tap, not just the kitchen.
• No chemicals added to your water, and no chlorine smell.
• Simple upkeep, with service from the same local team that installed it.

What UV needs to work well

The UV lamp is sized to your home’s flow rate so every gallon gets the treatment it needs. The sediment filter and softener ahead of it keep the quartz sleeve clear, and the lamp and sleeve need simple routine upkeep. We’ll set up a service schedule with you.

Keep an eye on the well

UV treats the water, but the well still needs care. The CDC recommends checking your well every spring to make sure there are no mechanical problems, and testing at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH [CDC: Guidelines for testing well water]. We’ll remind you when it’s time.

Well water bacteria near you

We help well owners across the corridor: Manteca · Lathrop · Stockton · Patterson · Hughson · Turlock · Modesto.