This is a water-based sewer system in which Blackwater is transported to a Centralized or Semi-Centralized Treatment facility. The important characteristic of this system is that there is no Collection and Storage/ Treatment. Inputs to the system include Faeces, Urine, Flushwater, Anal Cleansing Water, Dry Cleansing Materials, Greywater and possibly Stormwater.
There are two User Interface technologies that can be used for this system: a [[Pour Flush Toilet | Pour Flush Toilet]] (U.4) or a [[Cistern Flush Toilet | Cistern Flush Toilet]] (U.5). A [[Urinal |Urinal]] (U.3) could additionally be used. The Blackwater that is generated at the User Interface together with Greywater is directly conveyed to a (Semi-) Centralized Treatment facility through a [[Simplified Sewers Sewer | Simplified]] (C.4) or a [[Conventional Gravity Sewer | Conventional Gravity Sewer network]] (C.6).
Stormwater could also be put into the [[Conventional Gravity Sewer |Gravity Sewer] network, although this would dilute the wastewater and require Stormwater overflows. Therefore, local retention and infiltration of Stormwater or a separate drainage system for rainwater are the recommended approaches.
This system is most appropriate when there is a high willingness and ability to pay for the capital investment and maintenance costs and where there is a pre-existing treatment facility that has the capacity to accept additional flow. Guidelines for the safe use of Effluent and Sludge have been published by the World Health Organization (WHO) and are referenced on the relevant technology information sheets.
[[Functional Groups|More on the Functional Groups: U, S, C, T, or D]]
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[[Image:blackwater system chart.png|none|1000px|]]
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