CNMI Lead and Copper Sample Site Tiering System
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If you are a Community Water System (CWS)
Tier 1 sampling sites are single family structures that:
Note: Due to the very aggressive nature of RO water and pure (unmixed) rainwater, PWS that provide these types of water as their main source for drinking purposes (where consumers actually drink the water) must collect at least 50% of their lead & copper samples from these sites. This is required even if the limited number of sampling sites requires these samples to be collected over several days.
Note: When multiple-family residences (MFRs) comprise at least 20% of the structures served by a water system, the system may count them as Tier 1 sites.
Tier 2 sampling sites consist of buildings, including MFRs, that:
Tier 3 sampling sites consist of single family structures that:
- have copper pipes with lead solder installed after 1997
- contain lead pipes
- are served by lead service lines
- are provided water that your utility centrally treats with reverse osmosis (RO)
- are provided rainwater (collected via rain catchments) that is not mixed with another source
Note: Due to the very aggressive nature of RO water and pure (unmixed) rainwater, PWS that provide these types of water as their main source for drinking purposes (where consumers actually drink the water) must collect at least 50% of their lead & copper samples from these sites. This is required even if the limited number of sampling sites requires these samples to be collected over several days.
Note: When multiple-family residences (MFRs) comprise at least 20% of the structures served by a water system, the system may count them as Tier 1 sites.
Tier 2 sampling sites consist of buildings, including MFRs, that:
- have copper pipes with lead solder installed after 1997
- contain lead pipes
- are served by lead service lines
- are provided water that your utility centrally treats with reverse osmosis (RO)
- are provided rainwater (collected via rain catchments) that is not mixed with another source
Tier 3 sampling sites consist of single family structures that:
- have copper pipes with lead solder installed before 1998
- are provided rainwater (collected via rain catchments) that is mixed with another source
If you are a Non-Transient Non-Community Water System (NTNCWS)
Tier 1 sampling sites consist of buildings that:
Note: Due to the very aggressive nature of RO water and pure (unmixed) rainwater, PWS that provide these types of water as their main source for drinking purposes (where consumers actually drink the water) must collect at least 50% of their lead & copper samples from these sites. This is required even if the limited number of sampling sites requires these samples to be collected over several days.
Tier 2 sampling sites consist of buildings that:
Tier 3: Not applicable
- have copper pipes with lead solder installed after 1997
- contain lead pipes
- are served by lead service lines
- are provided water that your utility centrally treats with reverse osmosis (RO)
- are provide rainwater (collected via rain catchments) that is not mixed with another source
Note: Due to the very aggressive nature of RO water and pure (unmixed) rainwater, PWS that provide these types of water as their main source for drinking purposes (where consumers actually drink the water) must collect at least 50% of their lead & copper samples from these sites. This is required even if the limited number of sampling sites requires these samples to be collected over several days.
Tier 2 sampling sites consist of buildings that:
- have copper pipes with lead solder installed before 1998
- are provided rainwater (collected via rain catchments) that is mixed with another source
Tier 3: Not applicable
Note for All Water Systems
Do not designate Lead & Copper sampling sites on distribution systems that:
- serve only a transient population, or
- provide unmodified CUC water (i.e., CUC water that you do not treat or you do not mix with well/rain catchment water).
Other Sampling Sites
Your public water system (PWS) may not have enough Tier 1, Tier 2 or Tier 3 sampling sites to meet the minimum number of sites required under the Lead &Copper Rule. In this case, you must designate other sampling sites that do not fall under the tiering system shown above. When doing this, you should prioritize sample sites from the locations shown below. These sites potentially have a higher risk of lead and copper contamination than other locations in your distribution system.
- Areas of new building construction or plumbing within the last 5 years;
- Areas of the distribution system serving water with low total dissolved solids or chloride concentrations;
- Bronze or brass faucets, copper fittings, and areas with plumbing pipes, fittings or fixtures of unknown composition.
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Copyright (c) 2009 - 2016 Mariana Islands Water Operator Association
Last Modified: 3/10/2016
Copyright (c) 2009 - 2016 Mariana Islands Water Operator Association
Last Modified: 3/10/2016