Whole house water filtration, purification, softening, and sterilization

Whole house water filtration, purification, softening, and sterilization

Now that we had successfully undertaken water conservation in our Passive House, we were left with ensuring water quality at the tap.

My understanding is having a deep underground water source is actually quite good.  Wells that are much shallower may be adversely affected more quickly during periods of drought than deeper wells.   Additionally shallower wells may be subject to higher levels of water contamination from pesticides and fertilizers that can occur from water run-off.


Water quality testing is required in our area prior be able to receive an approve-to-use permit.  While not required nor typically conducted, Lisa and I opted for an additional water quality test--the testing of water-borne Radon.  Radon is a radioactive noble gas that occurs naturally in the ground from radioactive decay of uranium and thorium.  Isotopes have varying half-lives from very short to extremely long.  It is colorless and tasteless.

Outside of smoking, Radon is a major contributor to lung-cancer.  I like to think of it as a silent killer.  Given the extreme air-tightness of Passive Houses (even with mechanical ventilation) and especially with the use of earth air tubes, I strongly recommend getting the interior air quality of your home tested for Radon.

Radon readily dissolves in water, which is why we tested for it.  And while it is true, Radon is less dangerous while it is dissolved in water, it can and does come out from its dissolved state and back out into the air in gaseous form.

Fortunately, in both forms, Radon mitigation is easy.  In both instances activated charcoal filtering can do the trick (and in the case of Radon gas in the basement a sub-slab air pump which creates negative pressure to evacuate the gas to the outside).  Water softening can also remove Radon.  But please keep in mind that filters will need to be replaced periodically, since build-up will occur in the filter.

5 micro triple water filtration system

Whole House Water Filtration

Deep well water can have a wonderful taste to it, as is the case with us.  However there can and often is impurities, which are not desired--especially after a hydrofrac.  We selected a large three stage filtering system starting with 20 microns and finishing with 5 microns.  Not only were we able to filter out non-dissolved particles, but also some material that remains dissolved in the water.  These filters can also help mitigate turbidity.  We used a three-stage filtering system that utilized 1" connectors to ensure as high flow rates as possible.

Whole House Water Softening

Lisa and I debated using a water softener.  There is some debate as to whether water softening is helpful or detrimental to onsite in-ground septic systems as the sodium may have impacts on aerobic and anaerobic processes.  We ultimately decided to install an ion-exchange water softener, although the system can easily be bypassed if we so chose.  The unit we selected is computer controlled to minimize the use of salt.  Furthermore, we opted to use potassium, as opposed to sodium as potassium use is not associated with elevated levels of blood-pressure and has some positive health-effects (similar to eating bananas).  Water softeners such as these can also reduce levels of turbidity and iron in the water, which is a good thing in our case as we have elevated levels of iron in our water supply due to extensive amount of subterranean ironstone on our lot.

Sterilight UVC Whole-House Water Sterilization System

Whole House UVC Water Sterilization

After filtration and (optional) water softening, our water supply passes by an Ultraviolet light source emitting high-energy UVC light.  This lethal form of UV light kills most pathogens that may lurk in our water, including bacteria and viruses as well as other potential "nasties."  Sterilization occurs without the use of chemicals (always a good thing).  The UVC light bulbs need to be changed every year and can be done so without interruption to the water supply.  Be very careful in removing and installing the replacement bulb, however.  We found out the hard way when I went to replace the unit, I cracked the outer crystal tube that encases the bulb.  Crystal is the only material that can withstand extended exposure to UVC light and its very expensive (not to mention sharp).

Multiple Point-of-Use Reverse Osmosis

The final step in our water treatment occurs in an RO unit.  Reverse osmosis is only used in the cold water supply to our refrigerator and its ice maker; our plumbed commercial-grade espresso/cappuccino/coffee maker; and a dedicated faucet in our kitchen used for cooking.

To be sure, the taste of RO'd water is less satisfying and "flat" as compared to our water that has not passed through RO filtration.  However we wanted our ice cubes and water supply to our java maker and for our cooking to be entirely neutral.  It's very cool to see ice cubes that are clear and not cloudy.  Reverse osmosis does that and our coffee tastes wonderful.

Overall I would say that our water tastes better than any bottled spring or mineral water that I have had (save perhaps for Saratoga Spring water).  In fact, I enjoy drinking our water at room temperature where the "mineral" flavors are most noticeable and pleasant tasting.  In any event, our water production is a hell of a lot more environmentally friendly than using bottled water, which is extremely detrimental to our environment!

A bit of advice that I would like to impart in helping maintain the quality of water that we drink and yes this applies to users of public water (where do you think your water ultimately comes from?): properly dispose of unused medications (such as anti-biotics).  Do not discard medications into the sewage or refuse system, take them to a pharmacist for proper disposal.  The chemicals make it into the water supply and contribute to the ever decreasing effectiveness of antibiotics leading to more resistant strains of bacteria as a direct consequence.

Also, avoid the use of chemical fertilizers and fertilizing services.  These chemicals ultimately make their way into our ground source water supply.  There are far better and less environmentally destructive ways to maintain your landscape.