Coliform Monitoring Frequency Required at Public Water Systems Based on Population

The table below indicates the number of total coliform samples a community water system must take each month based on the population served. For example, a water system that serves a population of 9,200 must take at least 10 total coliform samples each month.

Monthly Coliform Samples Required for Community Water Systems
Population Range # samples per month
25 to 1000
1
1001 to 2500
2
2501 to 3300
3
3301 to 4100
4
4101 to 4900
5
4901 to 5800
6
5801 to 6700
7
6701 to 7600
8
7601 to 8500
9
8501 to 12900
10
12901 to 17200
15
17201 to 21500
20
21501 to 25000
25
25001 to 33000
30
33001 to 41000
40
41001 to 50000
50
50001 to 59000
60
59001 to 70000
70
70001 to 83000
80
83001 to 96000
90
96001 to 130000
100