Allerton Supply and Install Sewage Treatment Plant and Packaged Pump Stations for raw sewage, dirty water and storm water. The Allerton ConSept is for the conversion of Septic Tanks and Cesspools. We also offer Servicing, Maintenance and Repair on all makes of Sewage Treatment Plant and Pump Stations. Allerton has achieved British Water ?Accredited Service Engineers? status and has the CHAS Certificate.