The  National  Discussion   about  Disinfectant   Residual  in  Distribution   Systems November  24,  2015 Distribution  System  Disinfectant  Residuals Outline • History  and  Current  Federal  Framework • Proposed  State  Framework • What  do  we  know  now  that  we  did  not  know  then?     – Public  health  impact – Increased  knowledge  about  Distribution  System  water  quality • 2015  National  Expert  Panel  on  Distribution  Disinfectant  Residuals   (AWWA  Water  Industry  Technical  Action  Fund  262)   – Recommendations  to  EPA  for  updating  requirements – Research  Needs  and  Next  Steps Distribution  System  Disinfectant  Residuals Federal  Regulatory  Framework  -­ History • 1975  – National  Interim  Primary  Drinking  Water  Regulations   “A  supplier  of  water  …  with  the  approval  of  the  State  …  [may]  substitute the  use  of   chlorine  residual  monitoring  for not  more  than  75  percent  of  the  (coliform)  samples   …  When  the  supplier  of  water  exercises  the  option  …   shall  maintain  no  less  than   0.2  mg/L  free  chlorine throughout  the  public  water  distribution  system  …” • 1987  – Proposed  Surface  Water  Treatment  Rule  – Subpart  H Systems “Maintain  a  disinfectant  residual  in  the  distribution  system  (measured  as  total  chlorine,   free  chlorine,  combined  chlorine,  or  chlorine  dioxide)  of  no  less  than  0.2  mg/L  in   more  than  5  percent  of  the  samples  each  month,  for  two  consecutive  months” • 1989  -­ Surface  Water  Treatment  Rule “The  residual  disinfectant  concentration  in  the  distribution  system,…cannot  be   undetectable  in  more  than  5  percent  of  the  samples  each  month,  for  any  two   consecutive  months  that  the  system  serves  water  to  the  public.  …” – Source:  Pressman  (WQTC  2014) Distribution  System  Disinfectant  Residuals Federal  Regulatory  Framework  -­ History • Intent  behind  Surface  Water  Treatment  rule  residual  requirements: 1. Distribution  System  integrity   -­ Ensure  distribution  system  is  properly  maintained    &  have  ability  to  identify  and  limit   contamination  from  outside  system 2.  Limit  growth  (regrowth)  of  HPC  and  Legionella,   and 3.  Provide  a  quantifiable  minimum  target • Comments  on  1987  Draft   1. Many  low  HPC  systems  could  not  meet  0.2  mg/L  throughout  system 2. Increasing  chlorine  would  increase  DBPs 3. No  evidence  of  any  benefit 4. Requirements  should  be  different  for  different  disinfectants   • EPA  revised  rule   – require  “detectable”  in  lieu  of  0.2  mg/L.     – HPC  <500/mL  equivalent  to  detectable  residual   Source:  Pressman  (WQTC  2014) Distribution  System  Disinfectant  Residuals Federal  Regulatory  Framework • Summary  of  Current  requirements,  based  on  1989  SWTR 1. Residual  – total  chlorine,  free  chlorine,  or  chlorine  dioxide 2. Measured  at  same  locations  as  TCR  sites 3. Cannot  be  “undetectable”  in  >5%  of  samples  each  month,  for  2   consecutive  months 4. HPC  <500/mL  considered  equivalent  to  a  detectable  residual • EPA  Comments  on  1989  SWTR • Disinfectant  residuals  not  a  direct  measure  of  performance  but  an  indicator   of  system  integrity Note  intrusions   can  occur  in   • Presence of  disinfectant,  regardless  of  strength,  is  a  useful  indicator any  system,  not   • Differences  in  disinfectant  efficacy  taken  into  account  at  Treatment just  Surface   Water Plant  (primary  disinfection) • Major  purpose  of  maintaining  residual  is  to  indicate  if  local  contamination   occurring  – intrusions  into  system   Source:  Pressman  (WQTC  2014) State  Regulatory  Framework What  are  current  minimum  numeric  residual  requirements  set  at? DRAFT  State  Summary * * * Current   #  of   Requirement States # Detectable   22 Residual Numeric  Minimum 28 Residual Source:    Ingels (2014)  – modified  and  updated Note:    “*”  indicates  numeric  minimum  residual  less  than   0.2  mg/L;  “#”  numeric  criteria  limited  to  total  chlorine Distribution  System  Disinfectant  Residuals Proposed  Regulatory  Framework  – PA   • Pennsylvania  EQB  proposal,  passed  November  17,  2015 • Disinfectant  Residual  Monitoring – Same  time/locations  as  TCR – Representative  locations  are  monitored  once/week  (TCR  samples  can  count  towards  this) – Sample  plan  required  and  notification  to  DEP  within  30  days  of  a  change. • Minimum  disinfectant  residual  Limit  →    0.2  mg/L  (or  ≥0.15mg/L) – Applies  to  CWS,  NTNC,  &  TNC  systems  that  use  a  chemical  disinfectant – HPC  out  for  measurement  of  <500/mL  will  only  apply  to  bottled  water  facilities – Measured  as  Total  Chlorine for  Chloramine  Systems – Measured  as  Free  Chlorine for  Chlorine  Systems • Treatment  Technique  Violations: – PWS  ≤  33,000  – have  more  than  1  sample  below  limit  two  consecutive  months – PWS  >  33,000  – have  more  than  5%  samples  below  limit  two  consecutive  months – Reporting:    Notify  DEP  within  1  hour  and  Tier  2  PN • Locations  below  limit  two  consecutive  months – Root  Cause/Corrective  Action  Reports  required • Nitrification  control  plan  required  for  Chloramine  systems  (AWWA  M56). Distribution  System  Disinfectant  Residuals What  has  changed  from  Public  Health  Perspective? • CDC,  Morbidity  and  Mortality  Weekly  Report  – September   6,  2013;;  Surveillance   for  Waterborne  Disease  Outbreaks  Associated  with  Drinking  Water  and  Other   Nonrecreational Water  — United  States,  2009–2010 Distribution  System  Disinfectant  Residuals What  has  changed  from  Public  Health  Perspective? • CDC,  Morbidity  and  Mortality  Weekly  Report  – September   6,  2013;;  Surveillance  for   Waterborne   Disease  Outbreaks  Associated  with  Drinking  Water  and  Other  Nonrecreational Water  — United  States,  2009–2010 • 33  drinking  water  outbreaks,  1040  illnesses,  9  deaths • 58%  of  outbreaks  legionella • Most  commonly  identified  deficiency   – 57.6%  legionella in  plumbing  systems – 24.2%  untreated  groundwater – 12.1%  distribution  system  deficiencies   • Groundwater  sources • Cross  connections Distribution  System  Disinfectant  Residuals What  has  changed  from  Public  Health  Perspective? • CDC  also  recently  summarized  the  following  for   Waterborne  hospitalizations  and  deaths – Enteric  pathogens  (e.g.  e.  coli)  :  lower – Biofilm  pathogens  (e.g.  legionella):  higher – Classic  fecal-­oral  waterborne  disease  occurs,  but   seldom  results  in  death  in  US – Patients  infected  with  biofilm  associated  disease  may   have  a  more  complex  clinical  picture  than  GI  illnesses   Source:  Julie  Gargano,  CDC WQTC  2014   Public  Health  Importance  of  Premise  Plumbing  Pathogens