Legislation providing for the inspection and registration of septic tanks has just been published according to page two of today’s Irish Times.  The legislation is coming under fire from Opposition who suggest that it is full of hidden charges for home owners with septic tanks.  It seems that a first inspection is free with any additional inspections coming in at €200 a go, this may also be on top of a €50 registration fee and the cost of any necessary upgrade works. Original costs proposed by the department were €50 per inspection and would be required to take place every five years. The legislation also suggests that inspections will be concentrated on areas with higher risk to the environment.

We thought it would be interesting to have a look at the location of these ‘high risk’ areas. However, to develop an accurate picture of this a lot of data would be required – geographic location and age of septic tanks, water features, soil types etc. For the moment we are therefore just going to concentrate on the location of septic tanks across the country.

By using 2006 Census data (http://www.cso.ie/census/Census2006_Volume6.htm) we can get a reasonably accurate picture of the number and distribution of septic tanks across the country. It must be noted that this is based on what was recorded on the census forms, enumerators didn’t go digging around in back gardens to verify. So, according to the census in 2006 there were a total of 1,462,296 total private dwellings in permanent housing units in Ireland, of these 418,033 had individual septic tanks, this equates to 28.6% of housing units. The vast majority of housing units are connected to public schemes (956,239 or 65.4%), almost 37,000 (2.5%) housing units have other types of individual sewerage systems that are not septic tanks and a total of 4,179 housing units have no sewerage facilities at all. Another 47,181 or 3.23% were recorded as ‘Not Stated’.

If we look at the spatial distribution of the estimated 418,033 septic tanks throughout the country there is a clear spatial pattern. It’s generally low in urban areas as housing units are all, or should be, linked to public schemes. As expected, the highest concentrations of septic tanks are within areas outside the main cities and towns. Map 1 below details this distribution and highlights particularly high concentrations in areas of east Meath, and the city environs of Cork, Limerick and Galway.  On a county by county basis the highest numbers of septic tanks are in Cork County, Galway County, Donegal, Kerry and Mayo. The lowest numbers are within the main cities – Limerick, Cork, Waterford, Galway and the Dublin Local Authorities

If we standardise the results by total number of households we start to get a different picture with the highest proportions within more rural areas. Map 2 details this distribution and shows very high proportions within County Galway (67.94%), Roscommon (61.48%), Donegal (56.38%), Leitrim (55.92%) and Mayo (54.88%). Again, the proportions within the city areas are extremely low with all below 4%.


Justin Gleeson