Today I Learned . . .

1.  The 4-3-2-1 Rule (my name for it)

The Policy statement requirements are as follows:

4-log removal/inactivation of viruses

3-log removal/inactivation of Giardia cysts and Cryptosporidium oocysts

2 treatment processes, usually filtration and disinfection

1 NTU turbidity (maximum) in the finished water

Be aware that the 1 NTU turbidity (maximum) becomes 0.1 NTU if you use a membrane process.