Holding Tanks for Floor Drains

Holding tanks that receive wastewater from floor drains in areas where regulated contaminants¹ are used or stored or that will receive non-domestic, non-hazardous wastewater must be registered with the Water Division of the N.H. Department of Environmental Services under N.H. Administrative Rules Env-Ws 1508.03 Holding Tank Registration for Discharges of Nondomestic, Nonhazardous Wastewater.

What Are DES’s Requirements for Holding Tanks?

• The minimum holding tank capacity must be 1,000 gallons.
• Holding tanks and piping must be watertight and sealed with materials compatible with the liquid or sludge being stored.
• Access must be provided to each compartment of the tank for inspection and cleaning by means of either a removable cover or manhole (minimum diameter 20 inches). Manholes must extend to finished grade.
• The tank must be designed for the expected maximum structural load and ballast must be provided when necessary to prevent structural damage when the tank is emptied.
• The volume between inlet cover and the maximum water depth must be equal to approximately 20 percent of the liquid volume stored below the maximum water depth. An alarm with both visual and audio signals must be activated once the water level reaches the maximum water depth.
• The holding tank must be registered with DES. Use the form on the reverse side of this fact sheet.
• Records of pumping events shall be kept and made available for review if requested by DES.

For Additional Information
For more information about holding tanks please visit the DES Drinking Water Source Protection webpage at www.des.nh.gov/dwspp, or call (603) 271-2858. For additional information, please contact the Drinking Water and Groundwater Bureau at (603) 271-2513 or dwgbinfo@des.state.nh.us or visit our website at www.des.nh.gov/dwgb. All of the bureau’s fact sheets are on-line at www.des.nh.gov/dwg.htm.

Note: This fact sheet is accurate as of January 2007. Statutory or regulatory changes, or the availability of additional information after this date may render this information inaccurate or incomplete.

Registration Form [PDF]