Our Wa­ter Qual­ity


For pub­lic wa­ter sys­tems, dis­in­fec­tants are widely and suc­cess­fully used to pro­tect pub­lic health and to en­sure that wa­ter is safely con­veyed to the most dis­tant con­nec­tions. But for pri­vate well users, ad­di­tional pro­tec­tion such as ul­tra­vi­o­let (UV), chlo­ri­na­tion, or ozona­tion may be re­quired. We es­ti­mate that about 10 per­cent of our well-wa­ter cus­tomers opt for the more con­ve­nient UV dis­in­fec­tion sys­tems. That per­cent­age is prob­a­bly equally di­vided be­tween cus­tomers who sim­ply want the ad­di­tional peace of mind and cus­tomers who have ex­pe­ri­enced un­pleas­ant health is­sues from wa­ter­borne or­gan­isms. Med­i­cal pro­fes­sion­als, when di­ag­nos­ing the cause of in­testi­nal com­plaints, do not al­ways im­me­di­ately cor­re­late mi­cro­bi­o­log­i­cally con­tam­i­nated well wa­ter with its pos­si­ble symp­toms.

But in­stalling UV ster­il­iza­tion sys­tems is not sim­ply a plug-and-play op­er­a­tion, be­cause gthey have lim­i­ta­tions with re­gard to wa­ter qual­ity, in­clud­ing hard­ness, iron, and tur­bid­ity (clar­ity). We have seen am­a­teur in­stal­la­tions where UV sys­tems are in­stalled on rather com­plex wa­ter without proper pre­treat­ment and are placed first in an ar­ray of treat­ment com­po­nents. UV should be placed at the end of the treat­ment ar­ray. We have seen cases when the home­owner leaves the UV in place and sim­ply un­plugs it when suf­fi­ciently an­noyed by the count­down clock and its alarm that sig­nals when it is time for the an­nual bulb re­place­ment.

UV sys­tems should not be in­stalled on well wa­ter in the ab­sence of wa­ter testing. When harm­ful bac­te­ria are con­firmed by lab testing, af­ter UV is in­stalled and when­ever plumb­ing lines are dis­rupted, it is highly rec­om­mended that the well and plumb­ing in­fra­struc­ture be “shocked” us­ing chlo­rine or 7 per­cent hy­dro­gen per­ox­ide.

Chem­i­cal ap­proaches to dis­in­fec­tion work by killing the micro­organ­isms, but UV ster­il­iza­tion is a phys­i­cal process that pro­vides rapid and ef­fec­tive in­ac­ti­va­tion of bac­te­ria, viruses and pro­to­zoa, ren­der­ing them in­ca­pable of re­pro­duc­ing and in­fect­ing. UV light is in­vis­i­ble and oc­cu­pies the por­tion of the elec­tro­mag­netic spec­trum be­tween X-rays and vis­i­ble light. The range of the ger­mi­ci­dal UV wave­length is be­tween 200 and 300 nanome­ters (bil­lions of a meter), with the op­ti­mal ef­fec­tive wave­length for DNA ab­sorp­tion be­ing 254 nanome­ters.

Al­though chlo­ri­na­tion can also be used for well ster­il­iza­tion, UV of­fers the dis­tinct ad­van­tage of neu­tral­iz­ing pro­to­zoan par­a­sites such as Cryp­tosprodium and Gi­a­r­dia, which are chlo­rine-re­sis­tant. The pathogen Cryp­tosporid­ium gar­nered na­tional at­ten­tion in 1993 when more than 400,000 Mil­wau­kee res­i­dents be­came ill with Cryp­tosporid­io­sis from a chlo­ri­nated sur­face wa­ter sup­ply.

An­other ef­fec­tive tech­nol­ogy for neu­tral­iz­ing bac­te­ria, viruses and spores is ozona­tion. Ozone (O3) is sim­ply oxy­gen with an ex­tra mol­e­cule, which re­verts to pure oxy­gen, the only by-prod­uct of this chem­i­cal-free tech­nol­ogy, within min­utes. Ozone sys­tems typ­i­cally con­sist of ozone gen­er­a­tors lo­cated in­side at­mo­spheric wa­ter cis­terns in­stalled for low-vol­ume pro­duc­ing wells or wells that have se­vere sed­i­ment is­sues.

Without ques­tion, there are more op­por­tu­ni­ties for us­ing UV sys­tems to en­sure ster­il­iza­tion of well wa­ter and when prop­erly in­stalled and main­tained, and with ap­pro- pri­ate pre-treat­ment (as dic­tated by wa­ter chem­istry pa­ram­e­ters), UV ster­il­iza­tion is an ef­fec­tive and af­ford­able means of achiev­ing bac­te­riosta­sis. Other ad­van­tages for UV are that it is en­vi­ron­men­tally friendly and chem­i­cal-free and that no dis­in­fec­tion by-prod­ucts are cre­ated.

Stephen Wi­man has a back­ground in earth science (M.S. and Ph.D. in ge­ol­ogy) and is the owner of Good Wa­ter Com­pany and a mem­ber of the City of Santa Fe’s Wa­ter Con­ser­va­tion Com­mit­tee. He may be reached at 505-471-9036 and [email protected]­wa­ter­com­pany.com

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