Small Drinking Water Systems Response to Adverse

Policy

Category: Safe Water
Subject: Small Drinking Water Systems Response to Adverse
Division: N/A
Policy Number: CA.83.01.105
Effective Date: Mar. 1996

POLICY STATEMENT

It is the policy of the Wellington-Dufferin-Guelph Public Health to provide advice to the SDWS (Small Drinking Water Systems) community in meeting the current Drinking Water Standards to ensure that the potability of SDWS water supplies is maintained.

 

APPROVED BY

Rob Thompson  


Procedure

Category: Safe Water
Subject: Small Drinking Water Systems Response to Adverse
Division: N/A
Procedure Number: CA.83.02.105
Effective Date: January 31, 2012

PROCEDURE

  1. Establish whether or not the small drinking water system is chlorinated or unchlorinated.  If it is chlorinated, refer to CA.83.01.107 Municipal Systems Bacteriologically Unsafe Regulated Systems 170/03 for instructions.  If the system is not chlorinated refer to Procedure for Corrective Action for Small Drinking Water Systems (SDWS) not Currently Using Chlorine and regulations 318/319 for more information. The Medical Officer of Health determines if a boil water advisory is necessary.
  2. Upon receiving unsatisfactory water results, the owner/operator of the small drinking water system and the lab must notify Wellington-Dufferin-Guelph Public Health (WDGPH) immediately by phone of the adverse result and follow by fax.  Upon receiving an adverse result from the lab the SDWS Public Health Inspector (PHI) or designated Program Assistant shall generate an AWQI number from LRMA and inform the lab of this AWQI number. If the result is received on the weekend, an AWQI number shall be generated on the next business day.

Adverse water quality includes:

  • E.coli detected in any required sample; and
  • Total coliforms detected in any required sample.
  1. The answers to the following questions that are relevant to the situation should be established prior to choosing a course of action:
  • Did upstream or downstream samples show poor water quality?
  • Is other water quality data available on the samples collected?
  • Was the sampling location representative of the whole system?
  • Was it a fixed site, if not where was the sample taken?
  • Was any work done on the distribution or supply prior to sampling?
  • Have any mechanical difficulties or equipment failures occurred?
  • Has there been any undue demand on the reservoir?
  • Was the proper sample procedure followed?
  • Was the sample taken by the regular sampler?
  • When was the sample taken (date/time)?
  • Do historical records indicate a consistent problem?
  • Is the result from raw or treated water?
  • Is the ground water vulnerable to contamination from surface water, agricultural activity, sewage discharge, and intensive recreational use?
  • What corrective actions have been initiated?

Course of action for adverse drinking water parameter in systems under Ontario Reg. 319 and Ontario Drinking Water Standards:

Table 1

PARAMETER

1 SAMPLE/1 LOCATION

E.coli found in distribution or supply

Consider BWA based on answers to above. If BWA issued notify MOH and operator. Flush with Chlorine and re-sample as per note below.

Total Coliform found in distribution or supply.

Re-sample at same site. If positive, consider BWA based on answers to above and flush system with Chlorine and re-sample as per note below.

Re-sampling Procedure:

Distribution

Re-sampling should consist of a minimum of 3 samples, one taken from:

a)The same location as the sample that gave rise to the corrective action.
b)A location that is significant distance upstream from the location described in (a), if that is reasonably possible.
c)A location that is a significant distance downstream from the location described in (a), if that is reasonably possible.

No Distribution

One sample.

*** Consult the Procedure for Corrective Action for SDWS not Currently Using Chlorine and Procedure for Disinfection of Drinking Water in Ontario and Response to Adverse Drinking Water Quality Incidents, April 2009.

  1. If a boil water advisory is required, provide a Boil Water Advisory letter (HPD SW (L)2) to the owner/operator and have them deliver the notice to all water users.  A notice must also be posted in a conspicuous place.  Fact sheet How to Use Water Safely During a Boil Water Advisory (HPD SW (FS)13) (see Appendix #1) should be issued along with the advisory. Ensure the Ministry of Health and Long-Term Care is notified through their website.
  2. The owner/operator will be responsible for the collection and submission of all re-samples to their lab for analysis. If the second set of results are unsatisfactory after chlorination or remediation of the system a decision may need to be made to determine what options are available to the operator to provide potable water. This may include installing a disinfection device, upgrading the existing well or drilling a new well or using an alternative potable source.
  3. Upon receipt of two consecutive satisfactory samples, issue a Removal of Boil Water Advisory (HPD SW (L)3) to the owner/operator.  Contact the Ministry of Health by fax of the rescind notice.  Have the owner of the waterworks notify the water users.

REFERENCES AND RELATED FORMS, POLICIES AND PROCEDURES

Corresponding Policy:  CA.83.01.105 Small Drinking Water Systems Response to Adverse
CA.83.01.107 Municipal Systems Bacteriologically Unsafe Regulated Systems 170/03
HPD SW (L)2) Boil Water Advisory letter
HPD SW (FS)13 How to Use Water Safely During a Boil Water Advisory
HPD SW (L)3 Removal of Boil Water Advisory
Ontario Reg. 319 and Ontario Drinking Water Standards
Procedure for Corrective Action for SDWS not Currently Using Chlorine and Procedure for Disinfection of Drinking Water in Ontario and Response to Adverse Drinking Water Quality Incidents, April 2009

APPROVED BY

Rob Thompson