Napier City Council will be increasing their hunt for illegally installed downpipes from July.
Council infrastructure director Jon Kingsford said they will initially focus on areas Westshore, Onekawa, Taradale and Tamatea where there are high numbers of non-compliant homes.
Downpipes which were improperly installed could lead to storm water overflowing into wastewater during extreme weather conditions and result in overflows at manholes and wastewater pump stations.
Kingsford said council action was needed because the majority of people do not fix the problem.
"A rough estimate is that only 30 per cent of people attend to the issue proactively. Most people defer the work until they sell their property allowing inflow to occur for many years."
He said the council had been gentle on the issue with homeowners in the past but it needed to change.
"If homeowners won't act to disconnect their non-compliant pipes so that the city network is protected from being overwhelmed, we need to."
Kingsford said penalties will not be the priority in the first instance and that education of the effects of improperly installed downpipes was vital.
"Nobody wants wastewater overflows to the environment and we want people to understand the impact their behaviour can have."
He said the total number of illegally installed downpipes was unknown but speculated people didn't understand what impact their violation could have.
Kingsford said some residents have arranged their plumbing in such a way that contravened the wastewater bylaw that outlined the prevention of infiltration from roof downpipes, surface water runoff, overland flow and subsurface drainage.
He said the council needed to step in to keep the environment free of waste.
"The community have made it very clear that the environment is a priority to them. We want to ensure that our wastewater network performs as expected during storm events."
Kingsford said incorrectly fitted downpipes are noted on the home's land information memorandum and that home owners could request a council inspection to see if change would be needed.