New Hampshire Code of Administrative Rules
Env - Department of Environmental Services
Subtitle Env-Ws - Division of Water
Chapter Env-Ws 300 - NEW HAMPSHIRE DRINKING WATER RULES
Part Env-Ws 372 - DESIGN STANDARDS FOR SMALL COMMUNITY WATER SYSTEMS
Section Env-Ws 372.18 - Sizing of Storage Tanks
Current through Register No. 13, March 27, 2025
(a) The criteria specified in this section shall apply to small community water systems and to those NTNC water systems whose reliability is directly important to public health as specified in Env-Ws 372.02(g).
(b) The required atmospheric water storage capacity for a water system with only one well shall be based on the safe yield of the well and the water system's design flow, as specified in Table 372-3 below:
Table 372-3
Requirement for Atmospheric Water Storage Capacity
For Water Systems That Have Only One Source
| Groundwater Source Capacity | Atmospheric water storage capacityrequired |
| Peak flow | 50 percent of design flow |
| 2.5 times the design flow | 75 percent of design flow |
| 2.0 times the design flow | 100 percent of design flow |
| Less than 2.0 times the design flow | Not acceptable |
(c) The required atmospheric water storage capacity for a water system with more than one well shall be based on the safe yields of the wells and the water system's design flow,as specified in Table 372-4 below :
Table 372-4
Requirement for Atmospheric Water Storage Capacity
For Water Systems That Have More Than One Source
| Minimum groundwater source capacity with largest producing well out-of-service | Atmospheric water storage capacityrequired |
| Peak flow | none required |
| 2.5 times the design flow | 25 percent of design flow |
| 1.5 times the design flow | 50 percent of design flow |
| Design flow | 75 percent of design flow |
| Less than design flow | 100 percent of design flow |
(d) The required hydropneumatic storage capacity shall be 10 percent of total design flow .
(f) Pre-charged pressure storage tanks shall be accepted on an equivalent gross volume basis to conventional hydropneumatic storage. No more than 6 tanks of the pre-charged pressure type shall be permitted.
(See Revision Note at chapter heading Env-Ws 300) #6521, eff 6-4-97; ss by #8360, INTERIM, eff 6-4-05, EXPIRES: 12-1-05; ss by #8496, eff 11-30-05
