In this article we cover:

  • When to replace a septic tank
  • How to go about it
  • What grants are available to replace a septic tank
  • Situation in both Ireland and Northern Ireland

In an older sewer system, it is rare that the complete system fails at once. The main things which usually go wrong are the septic tank itself, the sub-surface irrigation system or other elements such as manholes, inspection chambers and gullies.

Septic tanks may become damaged due to changing ground conditions or the gradual breakdown due to ageing and chemical processes acting on the materials with which they were constructed. It is usually less costly to replace a septic tank which requires extensive repair, rather than repair it.

As discussed previously, the usual viable replacement in most cases will be a PWWTP. If space is limited, this may involve emptying the old system, digging it out and correctly disposing of the debris. If space is available nearby for the replacement system, the old one can be emptied of sewage and filled with a suitable inert fill material and the drains and other access fittings re-routed as required.

If a sub-surface irrigation system fails, it will usually be due to factors such as soil compaction, saturation of the soil, an incorrectly installed system, use of the wrong type of drainage pipes, silting up of the pipework or tree root damage.

Replacing a failed sub surface irrigation system will be easiest if an alternative area can be used, as long as the soil conditions are suitable. If no alternative area is available, a solution might involve the provision of a soakaway mound or similar alternative, but before carrying out any work, consult with the local Water Quality Unit (Northern Ireland) or the Rural Water Section in your local authority (Ireland) and act on their advice.

In Northern Ireland, for any sewage system failure which occurs at the existing tank or downstream of it, a new consent to discharge domestic effluent will be required to replace it. The processes and application fees for this are essentially the same as applying for a new consent.

Grants in Ireland

They’re hard to come by but worth investigating if your wastewater system needs an upgrade.

If your septic tank or domestic wastewater treatment system needs repair, upgrade or replacement, know that the Domestic Waste Water Treatment Systems Grant Scheme is available in Ireland.

Administered by local authorities, it can provide up to 85 per cent of eligible costs, to a maximum of €12,000, for approved remediation works.

In most cases, eligibility arises where a problem has been identified following a local authority inspection under the National Inspection Plan, and the homeowner has received formal notice that remedial works are required.

Separate grant routes may also apply in certain Prioritised Areas for Action or High Status Objective Catchment Areas, where local authorities issue eligibility letters in advance.

Note that you cannot request that your house be inspected, which makes the grant difficult to get if you are not in a high-risk area.

To qualify, the house must also be permanently occupied, at least seven years old, and not have received a similar grant within the previous seven years. Routine maintenance, servicing and desludging are not covered.

All approved works must comply with the EPA Code of Practice 2021. Contact the Rural Water Section of your local authority for more information.