This makes the sector a perfect candidate for public sector investment rather than private sector profitability. Governments can adopt a range of measures, including subsidies, to ensure that water and sanitation services remain affordable and meet the needs of marginalized groups. A fixed amount of water can be made available to all households at no charge, coupled with a stepped tariff for additional quantities (as in South Africa), bearing in mind that this could still underserve poorer households, which tend to be larger in size and may share a water connection. Alternatively, subsidies can be targeted to specific groups, based either on household income (as in Chile) or geographical location (Colombia).57 Another possibility is to cross-subsidize different public services. Many of these alternatives are financed by households themselves rather than by governments. It is thus necessary to regulate and subsidize their water sources.