In some cases, the poorest households may not be able to afford access to water services. Evidence in OECD countries suggests that affordability of water charges for low-income households is a politically sensitive issue. A variety of approaches have been deployed for this purpose; most involve either direct support from the public budget (e.g. additional direct income support for consumption and/or subsidised connection fees) or cross-subsidisation through the tariff structure (e.g. increasing-block water tariffs, where those who use only a small amount of water pay very little for it while higher levels of consumption are subject to higher tariffs). A balance must be struck between economic/ environmental efficiency and equity objectives.