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Helpful Hints to Pass Backflow Assembly Inspection

Please also refer to Denver Water’s Capital Projects Construction Standards details 32054, 33282 and 33283.

  1. For tap, service line and meter installation details, please see Helpful Hints to Pass Meter Inspections: small size meters, mid-size meters, large-size meters.
  2. Stop-and-waste valve must be 4.5- to 6-feet deep.
  3. Approved Reduced Pressure Backflow Prevention Assembly (RP) or Pressure Vacuum Breaker (PVB) must be installed 5 feet downstream from the meter pit or 10 feet downstream with the use of a stop and waste valve.
  4. RPs must be installed at least 12 feet above the concrete pad, PVBs must be installed at least 12 feet above the highest point of use (not shown; located inside enclosure).
  5. Backflow assembly enclosure (heated or non-heated) with service line address posted.
  6. Drain valve/control valve must be a maximum of 2 feet downstream of RP BFPA.
  7. Concrete pad must be 4 inches thick. Top of concrete slab must be 1 inch above finished grade.
  8. Branch lines for domestic use, as outlined in Denver Water’s Engineering Standards (see Appendix D), are not allowed off irrigation service lines.
  9. For all service lines 2 inches and smaller, service line material type must be installed as required in Denver Water’s Capital Projects Construction Standards (33-14-17) and Denver Water’s Engineering Standards (see Chapter 3.10) to the upstream side of the backflow preventer. Once downstream of the stop and waste valve, service line material type must be provided as required in Denver Water’s Capital Projects Construction Standards (32054, 33282 and 33283).