Industry Definitions

In addition to definitions used in the Uniform and International Plumbing Codes, the following definitions apply to rainwater harvesting systems:

1. AUXILIARY SUPPLY: Water supply that is arranged and protected from contamination and is available to provide an alternate means of filling a cistern.

2. CALMING INLET: A device that permits water to enter a storage tank with minimal disturbance to particles that may have settled to bottom of the tank. See Quiescent Flow.

3. CISTERN: The central storage component of the rainwater harvesting system. Protection and maintenance of the cistern is essential for the health of the system.

4. CODE: Refers to the local written authority i.e. the Uniform Plumbing Code, International Plumbing Code, NSF International, etc.

5. COLLECTION AREA: Area from which rainwater is collected for use in a rainwater harvesting system (e.g. roof area).

6. DEBRIS EXCLUDER: A screen or other device installed on the gutter or down spout system to prevent the accumulation of leaves, needles, or other debris in the system.

7. DISINFECTION: Reduction of viable micro-organisms to a level that is deemed suitable for the intended application. Typical units of measure are Colony Forming Units per deca-liter (cfu / dl).

8. DRY RUN PROTECTION: System for protecting the water pump against running dry.

9. EVAPORATION FIELD: Element in the ground that is filled with gravel, ballast or special non-permeable plastic elements and that stores rainwater that is fed into it on an intermediate basis before the water evaporates into the atmosphere or seeps into the surrounding soil.

10. FILTRATION: Physical removal of liquid-borne contaminants by means of separation from the output flow. Particulate filtration removes suspended particles (measured in units of Total Suspended Solids (TSS); while other forms of filtration, such as carbon / absorption filtration, removes dissolved compounds measured in units of Total Dissolved Solids (TDS).

11. GROUND WATER: Water that saturates into the ground and no longer flows across the surface, it is considered “Groundwater”

12. FIRE SPRINKLER RESERVE: Volume of water needed for fire protection that is not available for any other use and accessible only by the fire pump

13. FLAT: Having a slope no greater than 1 in 50.

14. HARVESTED WATER: Process water system for utilizing rainwater for potable, non-potable, industrial or irrigation application.

15. LEACH FIELD, EVAPORATION / TRANSPIRATION FIELD: Element in the ground that is filled with gravel, ballast or special permeable plastic elements and that stores rainwater that is fed into it on an intermediate basis before the water seeps into the surrounding soil.

16. MINIMUM WATER VOLUME: Recoverable water volume that is constrained by the process such that neither sediment nor scum can be sucked into the deliverable water.

17. OVERFLOW LEVEL: The highest level that water from a drainage system can rise to.

18. OVERFLOW LINE: Line for leading away rainwater when the rainwater reservoir is full, e.g. into the sewage system or a seepage system

19. PIPING SYSTEM: Pipes that conveys the harvested rainwater and distributes it to various fixtures.

20. POINT OF USE: A point in a domestic water system, nearest to a water consuming plumbing fixture, where water is used.

21. PRECIPITATION: Water that has precipitated from the atmosphere (e.g. rain, snow, mist, dew)

22. PRECIPITATION CHARACTERISTICS: Characteristics of a precipitation event (e.g. intensity, duration)

23. PRIVATE WATER SYSTEM: System used by less than 25 persons over a 60 day period.

24. PROCESS WATER: Water to be used for household and commercial applications.

25. PROCESS WATER LINE: System of lines from the process water pump to the individual points at which water is drawn.

26. PROCESS WATER PUMP: Pumps process water from the rainwater reservoir to the points at which it is drawn.

27. PROCESS WATER REQUIREMENTS: Planning value for the process water amount that is expected to be required in a specified period of time.

28. PUBLIC WATER SYSTEM: System that is used by 25 or more different persons over a 60 day period.

29. QUANTITY OF PRECIPITATION: Precipitation at a certain place, expressed as the water height over a horizontal area for a span of time under consideration .

30.QUIESCENT INFLOW: Routing of rainwater into rainwater reservoirs so that the existing sediment is not activated in the rainwater reservoir and an immediate sedimentation of solids is possible.

31. RAINWATER : Water from natural precipitation that was not contaminated by use.

32. RAINWATER HARVESTING SYSTEM: Water system for utilizing rainwater, consisting of a cistern(s), pipe, fittings, pumps and/or other plumbing appurtenances, required for and/or used to harvest and distribute rainwater.

33. RAINWATER LINE: Supply, drainage, overflow and emptying lines of a rainwater harvesting system.

34. RAINWATER YIELD: Net water volume (water inflow) ,determined over a certain period of time, available for use as process water. Typically this is approximately 80% of theoretical collectable rainwater.

35. RETURN ELBOW : A section of pipe with a 180-degree bend.

36. ROOF DRAINAGE SYSTEM: A system, comprised of roof drains, overflow drains, scuppers, gutters and down spouts, used to convey the rainwater from the roof surface to the roof washer and the cistern.

37. ROOF SURFACE : The surface rainwater harvesting systems rely on for the collection of rainwater that has fallen on a building roof.

38. ROOF WASH OR ROOF WASHER: A device or method for removal of sediment and debris from collection surface by diverting initial rainfall from entry into the cistern(s). Also called a First Flush Device

39. SCREEN: A filtration device, constructed of corrosion resistant wire or other approved mesh, having openings in determined sizes.

40. SEDIMENTATION: Separation of solids from the water via gravity.

41. SLOPE OR SLOPING: Having a slope greater than 1 in 50.

42. SUB-SURFACE IRRIGATION: Water that is applied below ground level, and is not directly exposed to the above ground surface and/or surrounding air.

43. SUCTION LINE: Water pump inlet piping.

44. SUN BARRIERS : A cover, or erected structure, specifically to shelter a cistern from the direct rays of the sun.

45. SUPPLEMENTAL SUPPLY: Equipment for providing a supplemental supply of drinking water or non-drinking water into process water systems

46. SURFACE IRRIGATION: Water that is applied above ground level and is directly exposed to the above ground surface and/or air.

47. SURFACE WATER: Any rain water that touches the ground and flows across the surface of the ground (roadway, parking surface, gully, creeks, streams etc.) to be termed “surface water”.

48. SYSTEM CONTROL UNIT: Control unit for the automatic operation of the rainwater harvesting system .

49. TRANSFER PUMP: A mechanical device to transfer collected water from down spouts to remote cisterns.

50.USEFUL VOLUME: Volume that can be completely used during operation (Typically .80 – .90 of storage volume).

51. YIELD COEFFICIENT: Ratio of the rainwater annually flowing into the rainwater harvesting system to the total amount of rainwater in the accompanying precipitation area , allowing for leakage, splashing, evaporation, etc. (Typically .75 – .90).