Health of­fi­cials aren’t sure it’s safe

Den­ver Wa­ter wants to dou­ble the amount of re­cy­cled wa­ter used in the city.

The Denver Post - - FRONT PAGE - By Bruce Fin­ley

Den­ver Wa­ter is ask­ing for state per­mis­sion to ex­pand the uses of re­cy­cled wa­ter — to in­clude flush­ing toi­lets in com­mer­cial build­ings, wash­ing cows and pigs at the Na­tional Western Stock Show, and ir­ri­gat­ing crops such as mar­i­juana.

This could in­crease the 80 or so big cus­tomers in metro Den­ver who al­ready tap a 70-mile net­work of un­der­ground pur­ple pipes car­ry­ing re­cy­cled wa­ter, cleaned to meet the drink­ing-wa­ter stan­dards that ap­plied in the 1980s.

But state health of­fi­cials aren’t sure it’s safe to al­low wider use.

A Den­ver Wa­ter plan calls for at least dou­bling the amount of re­cy­cled wa­ter the util­ity pro­vides, be­yond the cur­rent 2.6 bil­lion gal­lons a year to more than 5.6 bil­lion gal­lons by 2020.

Us­ing more re­cy­cled wa­ter could save money be­cause strip­ping away con­tam­i­nants to meet cur­rent drink­ing-wa­ter stan­dards in­creas­ingly re­quires costly, en­ergy-in­ten­sive treat­ment. And reusing wa­ter re­duces Den­ver’s need to siphon more H2O out of the over­tapped Colorado River. Den­ver’s mar­i­juana sec­tor, alone, could make a big dif­fer­ence.

Dope grow­ers have emerged as sig­nif­i­cant guz­zlers, feed­ing plants an es­ti­mated 146 mil­lion gal­lons a year of drink­ing wa­ter. That’s more than the 98 mil­lion gal­lons that metro Den­ver brew­ers use to make beer.

“This is where the world is go­ing,” Den­ver Wa­ter chief ex­ec­u­tive Jim Lochhead said. “Util­i­ties are ex­plor­ing this con­cept of ‘one wa­ter,’ the right wa­ter qual­ity for the right pur­pose, and mak­ing the most ef­fi­cient use of wa­ter.”

Ris­ing tem­per­a­tures from cli­mate change and ex­haus­tion of the river com­pel new ap­proaches, he said.

“The de­mands on our sys­tem are go­ing to in­crease sim­ply be­cause it is go­ing to be warmer. Peo­ple and plants are go­ing to be us­ing more wa­ter,” Lochhead said. “The prospects of a ma­jor new di­ver­sion project on the Colorado River are dif­fi­cult at best.”

The Colorado Depart­ment of Pub­lic Health and En­vi­ron­ment has raised mul­ti­ple con­cerns.

State wa­ter qual­ity staffers are re­view­ing “ad­e­quate con­trol of pathogens,” in­clud­ing the po­ten­tial for bac­te­ria to grow in the pur­ple pipes, an agency spokes­woman said. That’s be­cause ir­ri­ga­tion of crops for hu­man con­sump­tion could mean more peo­ple are ex­posed to bac­te­ria. They’re also eval­u­at­ing the po­ten­tial for salts to build up in soils and ground­wa­ter. And they’re look­ing at is­sues around build-up of “an­tibi­otic re­sis­tant genes” that re­cy­cled wa­ter could ac­cel­er­ate. (Bac­te­ria that de­velop re­sis­tance to an­tibi­otics can re­pro­duce and pass on that re­sis­tance, cre­at­ing many more an­tibi­otic re­sis­tant bac­te­ria.)

“We’re as much about wa­ter con­ser­va­tion as any­one else,” CDPHE di­rec­tor Larry Wolk said. “If there’s reuse po­ten­tial for that kind of wa­ter that doesn’t pose any type of health risk — or has an ac­cept­able health risk — then it is some­thing we def­i­nitely should con­sider.

“We won’t know un­til that tech­ni­cal as­sess­ment is com­plete if it is an ac­cept­able risk or not. Just be­cause it was OK in 1980 doesn’t nec­es­sar­ily mean it is OK to­day — be­cause we know a lot more, after nearly 40 years, than we knew then,” Wolk said.

“But we are all about reuse,” Wolk said, “whether it is pro­duced wa­ter, re­cy­cled wa­ter, gray­wa­ter — if there is an ac­cept­able health risk.”

A CDPHE meet­ing is sched­uled for next week to launch a rule­mak­ing process that will run through Au­gust 2018. Health of­fi­cials said they want to hear from all sides and said any new uses of re­cy­cled wa­ter won’t hurt peo­ple or the en­vi­ron­ment.

State rules cur­rently al­low use of re­cy­cled wa­ter for car wash­ing, land­scape ir­ri­ga­tion, in­dus­trial sys­tems and putting out fires.

For years, Den­ver Wa­ter crews have been cap­tur­ing waste­water, treat­ing it and send­ing it back through the city. It is wa­ter ini­tially di­verted from the Colorado River and moved through tun­nels un­der the Con­ti­nen­tal Di­vide. (Den­ver Wa­ter legally is limited to a one-time use of its other wa­ter that orig­i­nates here in South Platte River Basin, be­cause down­river agri­cul­tural pro­duc­ers have rights to use Den­ver’s “re­turn flows.”) The pur­plepipe wa­ter is clas­si­fied as non­potable, but util­ity of­fi­cials em­pha­sized it meets the stan­dards of wa­ter peo­ple were drink­ing in the 1980s.

The 80 cur­rent users of re­cy­cled wa­ter in­clude ir­ri­ga­tors and in­dus­trial plants, nine schools, 34 parks, five golf cour­ses and the Den­ver Zoo. The Den­ver Mu­seum of Na­ture and Science uses re­cy­cled wa­ter to run heat­ing and cool­ing sys­tems. Xcel En­ergy’s Chero­kee power plant uses about a third of Den­ver’s re­cy­cled wa­ter.

Colorado’s state wa­ter plan calls for in­creased use of re­cy­cled wa­ter to con­serve sup­plies. The plan sets a tar­get of cut­ting an­nual wa­ter con­sump­tion statewide by 130 bil­lion gal­lons — be­cause pop­u­la­tion growth and de­vel­op­ment is strain­ing sup­plies. It urges in­creased re­cy­cling of wa­ter to pre­vent de­struc­tion of rivers with a tar­get of reusing 19 bil­lion gal­lons a year by 2050.

State wa­ter con­ser­va­tion board mem­bers have ap­proved use of funds to de­velop smart reg­u­la­tions.

Den­ver City Coun­cil mem­bers also are in­ter­ested, con­sid­er­ing pro­pos­als to re­di­rect “gray­wa­ter” from show­ers and wash­ing ma­chines to flush toi­lets and ir­ri­gate gar­dens through sub­sur­face drip sys­tems. This house­hold waste­water has not yet moved into sew­ers — dif­fer­ent from the re­cy­cled wa­ter that Den­ver Wa­ter treats and cir­cu­lates through the pur­ple pipes.

Re­cy­cled wa­ter, be­cause it once con­tained urine, holds salts that are costly to re­move — re­quir­ing treat­ment pro­cesses that would clean the wa­ter to the point it could be deemed safe for peo­ple to drink.

Some Den­ver res­i­dents com­plain that re­cy­cled wa­ter used to ir­ri­gate parks may be killing pine trees. And Den­ver Zoo of­fi­cials, able to use re­cy­cled wa­ter for an­i­mals, have had to make fully treated drink­ing wa­ter avail­able for ele­phants to drink to com­ply with na­tional zoo stan­dards.

Cal­i­for­nia, Florida and Idaho al­ready have adopted health reg­u­la­tions al­low­ing use of re­cy­cled wa­ter for toi­let flush­ing and to ir­ri­gate food crops, ac­cord­ing to a re­cent Western Re­source Ad­vo­cates re­view.

“Re­cy­cling wa­ter in our towns and cities is crit­i­cal to stretch­ing Colorado’s limited wa­ter sup­plies so we have enough wa­ter now and into the fu­ture,” WRA engi­neer Laura Be­langer said. “And to in­crease wa­ter reuse, Colorado needs to broaden the range of ways re­claimed wa­ter can be used. The new uses pro­posed by Den­ver Wa­ter are an im­por­tant step in that di­rec­tion.”

Gabriel Scar­lett, The Den­ver Post

Work­ers on Wed­nes­day in­stall pur­ple pipes for non­potable, re­cy­cled wa­ter for ir­ri­ga­tion in Den­ver. In­for­mally dubbed the “Pur­ple Pipes Project,” such use of non­potable wa­ter for ir­ri­ga­tion would save the city money.

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