Over 70% of septic tanks in Mayo failed inspections last year, according to new figures released today by the Environmental Protection Agency.
Out of those that failed, 65% were fixed by the end of 2021.
Key findings of the report show over half of tanks tested nationally failed inspection and more than one quarter were a risk to human health or the environment.
Roscommon were bottom of the table with almost 80% of tanks failing an initial inspection with 45% of those being rectified by the end of the year.
Galway saw a 39% fail rate while Sligo and Leitrim saw 54% and 89% fail rates respectively.
EPA say householders should ensure their septic tanks are properly built and maintained and their wells are tested to protect their health.