Sir, – Your editorial of August 2nd describes a number of options for abstracting water from the Shannon to augment potable water supplies for Dublin. You discuss desalination as a possible alternative water supply, with wind power as a preferred energy source. I was sufficiently intrigued by your discussion that I viewed the website created by the Dublin Water Supply project team, where several additional options for new water supplies are described.
It is striking to me that an option with low environmental impact and strategic advantages appears not to have been discussed. I refer to advanced wastewater reuse. Several water-stressed cities and regions such as Singapore, Orange County, California and Queensland, Australia, have demonstrated that advanced treatment and indirect reuse of wastewater are not only feasible but also significantly less expensive than desalination and more reliable than conveying raw water from a reluctant and distant supplier.
It is not difficult to imagine an advanced and efficient reuse plant located at the mouth of the Liffey, producing water significantly cleaner than any currently supplied in Dublin. This supply could be distributed via a new pipeline back along the course of the Liffey to the major industrial water users, many of which are located close to the river. A remainder could be conveyed to one of the existing raw water reservoirs, where it would mix with surface water before being retreated and distributed. Alternatively, a proportion of the treated water could be injected and stored in an underground aquifer, if suitable strata exist, before being pumped from abstraction wells for retreatment and distribution.
There is no doubt that the Dublin region requires a significantly increased water supply and an improved distribution system as soon as possible. Supply from the Shannon basin is probably the best choice, if the necessary storage and pipeline development is feasible. But reuse should be considered in addition, since a highly reliable reserve supply of highly purified water located at the heart of the city would be a major strategic asset to the Dublin region. – Yours, etc,