To,
Municipal Corporation,
_____________ (City)
_____________ (State/ Province)
Date: _____________
Subject: Complaint regarding overflowing sewage / blocked sewage
Respected Sir,
I, _____________ (Your Name) a resident of _____________(Locality) and an active member of _____________ (Resident Welfare Association, etc.) would like to bring to your kind notice the extensive overflow of the sewage in the _____________(Area/ street/ lane, etc.). Due to this local residents have to face the detrimental effects of polluted water. The increasing amount of contaminated diseases is a growing concern. The _____________ (breakage/ overflowing) of the sewer line has been a concern for the last _________ (days/ week/ months) now.
As a result, a large portion of residents is exposed to health issues such as _____________ (skin problems, respiratory system problems, Hepatitis, etc.).The local roads are flooded with effluent/ wastewater, which is not tolerated by the people. Moreover, the stinking smell is unbearable.
This issue needs to be resolved on an emergency basis. As a concerned resident of your supervised locality, I humbly request that you take appropriate steps immediately.
Yours Sincerely
_____________ (Your Name)
_____________ (Address)
lettersdadmin 
Rahul Sharma