Sewage and refuse disposal businesses collect, transport, treat or arrange the safe disposal of wastewater and solid waste. Sewage services may include emptying septic tanks, cesspits and treatment plants, removing sludge, and dealing with waste from portable toilets or other on-site facilities. Some operators also provide maintenance or inspection of private drainage and wastewater systems, although this category does not necessarily include general plumbing or sewer repairs. Refuse services can cover scheduled collections from households, businesses and construction sites, as well as one-off removal of bulky items, green waste or mixed rubbish. Waste may be sorted for reuse or recycling, treated, or taken to an authorised disposal facility, depending on its type. Customers may be able to arrange containers or collection at agreed intervals.