level that review requests for tariff adjustments submitted by service providers. the earliest and best-known example is the regulatory agency ofwat, which was established for england and wales in 1989. some developing countries followed suit. they include chile (1990), colombia (1994), honduras (2004), kenya, mozambique (1998), peru (1994), portugal (1997), and zambia (2000). the review process is typically based on transparent and objective criteria set by law, in an attempt to move decision-making at least partly out of the realm of politics. the track record of these agencies has been diverse, usually mirroring the political and administrative traditions of each country. changes in water use in response to tariff increases the responsiveness of demand to a change in price is measured by the price elasticity of demand, which is defined as the percentage change in demand divided by the percentage change in price. the price elasticity of drinking water demand by urban households is typically low. in european countries it ranges between -0.1 and -0.25, i.e. the demand for water decreases by 0.1% to 0.25% for every 1% increase in tariffs. in australia and the united states price elasticity is somewhat higher in the range of -0.1 and -0.4. affordability and social protection measures in about half the oecd member countries, affordability of water charges for low-income households is or could become a significant issue, according to the oecd. in developing countries, the poor are often not connected to the network and often pay a higher share of their meager incomes for lower quantities of water supplied by water vendors through trucks. on the other hand, utility bills paid by those fortunate enough to be connected to the network are very low in some developing countries. different countries have introduced a variety of approaches to protect the poor from high water tariffs. affordability the affordability of water charges can be measured by macro- and micro-affordability. macro-affordability" indicators relate national average household water and wastewater bills to average net disposable household income. in oecd countries it varies from 0.2% (italy and mexico) to 1.4% (slovak republic, poland and hungary). in the largest oecd countries the share is 0.3% in the united states and japan, 0.7% in france and 0.9% in germany. however, micro-affordability is quite different. it measures the share of bills in the income of the poor, defined in an oecd affordability study as the lowest decile of the population. this share varies between 1.1% (sweden, netherlands, italy) and 5.3% in the slovak republic, 9.0% in poland and 10.3% in turkey. the oecd concludes that in half its member countries (15 out of 30), affordability of water charges for low-income households "is either a significant issue now or might become one in the future, if appropriate policy measures are not put in place." in developing countries the situation is more serious, not only because of lower incomes, but also because the poor are often not connected to the network. they usually pay a higher share of their meager incomes for lower quantities of water at often lower quality supplied by water vendors through trucks. on the other hand, utility bills paid by those fortunate enough to be connected to the network are often relatively low, especially in south asia. because of this situation the oecd does not recommend to use uniform "thresholds" for the affordability of water and wastewater bills. these "thresholds" are often quoted in the range of 3-5% of household income. social protection measures social protection measures to ensure that piped water remains affordable can be broadly classified into income support measures and tariff-related measures. income support measures address the individual customer’s ability to pay from the income side (through income assistance, water services vouchers, tariff rebates and discounts, bill re-phasing and easier payment plans, arrears forgiveness). an example of income assistance to poor users is the subsidy system applied in chile. tariff-related measures keep the size of water bills low for certain groups (e.g. refinement of increasing-block tariffs, tariff choice, tariff capping). examples of increasing block tariffs with a price of zero in the first block are found in flanders and south africa. another measure is the cross-subsidization using different tariffs for different neighborhoods, as practiced in colombia. a similar approach has been used at the national level in portugal. the portuguese economic water regulator carried out an affordability study that found out that 10.5% of the population paid more than 3% of their income for water and wastewater services. as a result, the regulator showed flexibility concerning tariff increases and tariff solutions in municipalities where affordability was a particular issue.