Below is an overview of the types of samples as required by the NNSDWA and the NNPDWR.  Each type of public water system (community, non-transient,
transient and consecutive) are required to conduct sampling.
Contaminant Group
 §404   Sampling Frequency
 Sampling Sites
Bacteriological Quality or “Bactee”

§404 NNPDWR
 Monthly samples required from the distribution
system and in accordance to a written site sampling
plan.
 The number of samples is based on the
population served by the water system.
Nitrate  •  §407 NNPDWR
 Groundwater: samples are collected annually at
each entry point to the distribution.

Surface water: samples are collected quarterly at
each entry point to the distribution.
 The number of samples is based on the
numbers of entry point to the distribution
systems.
Nitrite   •  §408 NNPDWR
 Groundwater and Surface water: Surface water
systems, combined surface and groundwater
systems, or GWUDI shall take the sample annually.
 One sample at each entry point to the
distribution system after treatment.
Inorganic Chemicals  • §405 NNPDWR
 These chemicals are sampled on a three year basis.
Groundwater systems are required to collect 1
sample every three years for each well.  Surface
water systems, combined surface/groundwater or
GWUDI shall take one sample at each sampling
point.
 One sample at each sampling point.
VOCs and SOCs Groundwater and Surface Water:
Volatile Organic Chemicals and Synthetic Organic Chemicals are required sample on a three year basis. The sampling point must be a representative
of the well or source of water after treatment.
  • Systems serving <3,300 people are required to sample one annual sample every three years.
  • Systems serving >3,300 people are required to sample two Non-Consecutive quarterly samples every three years.
Volatile Organic Chemicals  (VOCs)

§ 409 NNPDWR
 These chemicals are sampled on a three year basis.
The owner/operator is required to collect 1 sample
every three years.
 One sample at each entry point of the
distribution systems.
Synthetic Organic Chemicals (SOCs)
§410 NNPDWR
 These chemicals are sampled on a three year basis.
The owner/operator is required to collect 1 sample
every three year basis.
 The number of samples is based on the
numbers of entry point to the distribution
systems.
Asbestos  •  §406 NNPDWR
 Must collect one sample that is a representative of
each source and/or consumer’s tap served by
asbestos cement pipe.
 A sample is collected once every 9 years or
more if the MCL is exceeded.
Radionuclides  •  § 411 NNPDWR
 A sample is required every four years. If there are
exceedances, four quarterly samples are required.
 Groundwater and Surface water: Sample four
consecutive quarters every four years.
Lead and Copper • §700  NNPDWR
 System Size        Quarterly Samples Event       # of Samples Sites
3,301 to 10,000                40                                        20
501 to   3,000                   20                                        10
101 to      500                   10                                           5  
<100                                    5                                           5
Lead and Copper: When the system has successfully completed THREE ROUNDS of lead and
copper sampling, the system is required to monitor for lead and copper at the reduced number of
sites for one more year. After completing three years of monitoring without exceeding the action
levels, the system may be eligible for begin triennial monitoring.
Disinfectant Residuals, Disinfection Byproducts
and Disinfection Byproduct Precursors

§1100 NNPDWR
 All community and nontransient-noncommunity water systems need to comply with these
regulations:
  1. The regulations in this part establish criteria under which CWSs and NTNCWSs that add a
    chemical disinfectant to the water in any part of the drinking water treatment process must
    modify their practices to meet MCLs and MRDLs in §207 and §208, respectively, and must
    meet the treatment requirements for disinfection byproducts precursors in §1106.
  2. The regulations in this part establish criteria under which TNTCWSs that use chlorine dioxide
    as a disinfectant or oxidant must modify their practices to meet the MRDLs for chlorine
    dioxide in §208.


Monitoring Requirements
Navajo Nation Environmental Protection Agency • Public Water Systems Supervision Program