Health and water quality benefits of alternative sewerage systems in Metro Manila, Philippines

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This paper presents results of a household survey on the current sanitation and sewerage conditions in Metro Manila. The survey included a choice, measured in terms of the marginal willingness to pay (MWTP), between two alternative domestic wastewater treatment systems: 1) a sewerage system connecting individual households to a treatment plant through sewer lines; and 2) a combined drainage–sewerage system in which wastewater effluent flows with rainwater through flood canals and is intercepted for treatment only at a certain point in the waterway. With the second, the health improvement effect may be limited, but the cost can be significantly lower. The finding in favour of the combined drainage–sewerage system lends some support to this new approach in municipal wastewater treatment, which some other increasingly congested metropolises in Asian countries are likewise adopting, as an alternative to the more costly individual household sewer connections.