1. (a) Each component of a filter system shall comply with Env-Wq 1108.22(a)(1).

2. (b) Each filter system shall include the following:

   1. (1) A strainer such as a pressure-type sand filter, a diatomaceous earth pressure or suction filter, or a cartridge-type filter;
   2. (2) A flow meter that also meets the requirements of (c), below;
   3. (3) A pressure gauge and an air relief valve for each filter;
   4. (4) A sight glass in each waste line from filter to backwash; and
   5. (5) A set of instructions for operating and maintaining the system.

3. (c) Each flow meter installed on a PBF filter system shall be:

   1. (1) Capable of measuring flows that are at least 1.5 times the design flow rate;
   2. (2) Accurate within 10% of true flow;
   3. (3) Located where the operator or an inspector can read the meter in the normal course of operations or during a routine inspection, respectively; and
   4. (4) Installed in accordance with the manufacturer’s specifications.

4. (d) Pressure-type sand filters also shall comply with the following:

   1. (1) For low-rate rapid sand filters, the flow rate shall not exceed 3 gallons per minute per square foot of filter area;
   2. (2) For high-rate rapid sand filters, the flow rate shall not exceed 15 gallons per minute per square foot of filter area; and
   3. (3) Back wash flow rates shall be 10 to 15 gallons per minute per square foot of filter area.

5. (e) Diatomaceous earth pressure or suction filters shall comply with the following:

   1. (1) The flow rate shall not exceed 2.0 gallons per minute per square foot of filter area; and
   2. (2) Filter piping shall provide for circulation through the filter only or be capable of selection to discharge to waste.
6. (f) For cartridge-type filters, filter flow rates shall not exceed 0.375 gallons per minute per square foot of filter media.

7. (g) Filter backwash and wastewater disposal shall be as follows:

   1. (1) Sewage and other wastewater, exclusive of filter backwash and pool drainage, shall be discharged into either a public sewer or a subsurface disposal system approved under RSA 485-A:29-44 and Env-Wq 1000;

   2. (2) Backwash and pool drainage shall be discharged:

      1. a. Into a public sewer through an air gap of not less than one inch; or
      2. b. Disposed of in a location or system approved by the department pursuant to RSA 485:3, X, RSA 485-A:29-44, RSA 485-A:13, I(a), or Env-Wq 402; and
   3. (3) When a pool or spa at a PBF is drained by discharge to a public sewer, the free disinfectant residual shall not exceed 3 mg/L chlorine or bromine.

Source. #10577, eff 5-1-14 (See Revision Note #2 at chapter heading for Env-Wq 1100); ss by #13198, eff 5-1-21 (see Revision Note #3 at chapter heading for Env-Wq 1100) (formerly Env-Wq 1106.07)