A few days after the tenants emptied the underground septic tank in August 2021, sinks in the house were blocking and human waste was backflowing out of the gully trap.
They told the landlord, who said he would call the plumber but later claimed there was some difficulty getting one because of Covid-19 lockdown at the time.
As an interim measure, one tenant cut the grey water waste pipes to divert the flow, which went on the lawn.
Seven months passed, and no plumber came.
"The extended delay of over seven months to have a plumber attend and resolve the plumbing problem was unacceptable," tribunal adjudicator Michael Brennan said in the September 6 decision.
The tenants finally called the local authority and officials visited in March, recording evidence of previous overflows including toilet paper and faeces.
The official served the landlord a Health Act Notice, and a plumber attended shortly afterwards to fix the problem.
In an application to the tribunal, the tenants drew up a list of problems that Edwards had failed to address.
"Sewer human waste overflowing," the list read, "Hose for washing machine empties out of window. Kitchen water goes on the lawn."
Also on the list: "Bad mould bathroom."
A Healthy Homes Assessment report showed significant black mould in one bedroom, and smaller amounts in the hallway, toilet and one bathroom.
One of the tenants painted the bedroom with mould-inhibiting paint but it returned. At the tribunal hearing, Edwards confirmed it was caused by moisture from a roof leak.
Certificates from the tenants' doctor said he believed a number of their visits and treatments were due to aggravation by their living conditions.
Rats were also a problem, living and dying in the underfloor insulation which Edwards and one tenant had to remove in 2019 because of bad smells, but never reinstalled.
"The landlord failed to reinstall it. I find he committed an unlawful act and the assistance of the tenant in the removal does not absolve the landlord from his obligations since July 1, 2019," the decision read.
Edwards was ordered to pay the tenants $3520 in compensation and damages.