Proceedings of the International Symposium on Efficient Water Use in Urban Areas


About UNEP	UNEP offices	News centre	Publications	Calendar	Awards	Milestones	UNEP Store

United Nations Environment Programme
Division of Technology, Industry and Economics

Newsletter and Technical Publications
<Proceedings of the International Symposium on Efficient Water Use in Urban Areas
- Innovative Ways of Finding Water for Cities ->

WHOLE-SCALE REDUCTION OF WATER USE:
THE MEXICO CITY PROJECT

Presented by Cristianne Chauvet-Urquidi *

MEXICO CITY AND ITS WATER RESOURCES

With an urbanised area of 1300 square kilometres, the Mexico City Metropolitan Area is an overall example of the challenge posed by nearly 20 million people and 45% of the country’s commercial, services and industrial activity, to provide sufficient supply, proper allocation and disposal of water and wastewater services, efficiently maintain its infrastructure and manage through multiple institutions.

Situated 2,200 meters above sea level in the southern part of the Mexico Valley Basin, it is surrounded by mountains three to five thousand meters high. Once it had abundant surface and underground water resources, notably freshwater and saline lakes, rivers and springs. The Aztec city of Tenochtitlán, was founded in the fourteenth century on an island, growing over the main freshwater lake. They developed extensive engineering works for canal-ways, dykes for flood control and separate fresh from salt water, disposal of used water and an elaborate network of aqueducts to supply drinking water from numerous springs. The Spanish in the Sixteenth Century, continued to use many works for the new Mexico City, but the dykes were destroyed, making the area flood-prone. To control continuos flooding in the city, the basin was artificially opened in the XVIIth Century, draining the lake system. Springs provided fresh water up to the 1850’s, when, on the discovery of potable ground water, hundreds of wells were built. By the early 1900’s, increased ground water extraction and lake drainage dried natural springs and land subsidence became a serious problem. In the 1950’s, many wells were closed down to deter subsidence and flooding. At this time the city had a population of 4 million people. Since then, major engineering works have been built to reduce flooding in sunken areas, deep sewer systems to expel used and rain water from the Basin and to import one third of the needed water into the Valley of Mexico, at great costs to population and public budget.

It is governed by two separate different political jurisdictions, the State of Mexico and the Federal District. The Federal District is the seat of Mexico City, the nation’s Capital, with almost 10 million inhabitants. Mexico City is divided administratively and territorially into 16 delegations, with centralised water management services.

Ground water levels have been deepening and declining over the past century causing increasing regional land subsidence, reaching over 7.5 meters in the city centre. This phenomenon is exacerbating flood-prone conditions, damaging building foundations and infrastructure – mainly water and sewage systems -, becoming a public health risk from microbiological and chemical contamination of hazardous waste management.

In sum, water supply for Mexico City and its metropolitan area is becoming a major crisis.

Water provision, sources and difficulties
The total water provision for the Valley of Mexico is in average 62 m3 per second. 35 m3/sec. are assigned to the Federal District (Mexico City) and 27 m3/sec go to rest of the metropolitan areas.

There are three main water sources, the lesser supply only 2% from local surface springs. Over 1,100 wells underlying the metropolitan area provide 66% of the metropolitan water supply. And the third source of supply, of 34 % is brought into the valley from nearby basins, the Lerma and Cutzamala Rivers and lake systems located 60 km and 127 km away. Importing water requires transporting and pumping it through canals, aqueducts and pipes over 1000 meter high mountain range at great costs of electricity and treatment plants. It is then distributed throughout Mexico City’s 12,000 kms of primary and secondary lines that supply nearly 1,697,000 users. Additionally, very big users have well concessions with extraction quotas, also paying to use the sewer system.

Average per capita water use is estimated at 350 litres/person/day, including unaccounted for water, a very high consumption when compared to other cities, such as 280 lt.p.d. in Barcelona, 230 lt.p.d. in Hamburg or 160 lt.p.d. in Brussels.

Water loss and collateral effects
It is estimated that 37% of the total water supply of the Federal District is unaccounted for, mainly leaks in the public water lines, not including loss of water in private property. Aged and obsolete water pipes, deteriorated by corrosion or damaged by the continuos sinking of land levels, tectonic faults and earthquakes, heavy traffic and uncontrolled interference of the infrastructure (illegal connections), have had inadequate maintenance for years.

The city cannot have access to alternate water sources that can be exploited at reasonable costs. To exemplify, there is an ongoing project to import additional water by 5 m3/sec, with an estimated investment of one thousand million pesos per cubic meter/sec.

The best strategy is to save and prevent loss of water. Awareness and participation of the individual and collective consumer is as important as the recovery of unaccounted for water.

PLANNING AN INTEGRATED APPROACH FOR EFFICIENT WATER USE

Institutional Framework
A general prevalent attitude has been that water resources are state property, a constitutional right free of charge. As a result, water supply and drainage have been strongly subsidised for years, causing the sector severe financial deficits.

Water in the Valley of Mexico is managed by various federal, state, municipal and local institutions, loosely integrated and co-ordinated. Within the Federal District, bulk water allocation, initially regulated by the Ministry of Agriculture and Water Resources (SARH), was recently taken over by the National Water Commission (CNA); the Federal District’s local utility is the General Direction for Water Construction and Operation (DGCOH), responsible for distribution. And up to 1995, the collection of water bills, meters, metering and the billing services were handled by the Treasury Department of the Federal District.

The various institutions involved in the water sector in Mexico City have become unable to deal with the magnitude of the problems of demand to expand water supply systems or improve services, repair leaks nor treat wastewater, deal with illegal connections and improper use deter pollution of underground water tables.

Water dues are regulated by Fiscal law, billed and paid on a bimonthly basis. Up to 1996 the Treasury Department of the D.F. was responsible for water billing, collecting and execute legal actions to recover owed dues, apply surcharge, penalties, recovery costs, and even seizure of property, hardly ever executed. Its water register listed 1,340,860 users, billed under two modalities: estimated metered daily consumption and fixed tariffs for different urban socio-economic conditions. Many had obsolete user, property and address data. Neither billing methods encouraged meter installation, efficient water use, domestic maintenance of installations nor payment of bills. The average bimonthly revenue was only 30% the emission value and an enormous overdue debt was accumulated. Payments in banks and in the Treasury’s offices were not recognised opportunely in the users accounts. Only some 16,000 big users were being metered regularly and billed with metered service.

Mexico initiated in 1988, nation-wide major reforms for water resource allocation and management of water services, developing new laws and regulations, specific institutional structures, conservation measures, education programs and innovative conditions for public-private joint ventures, among others. The new National Water Law in 1992 called for State Water Commissions and local municipal operating organisms, with the intention that water become a common service, not a tax, as has happened in several cities.

The Mexico City Water Strategy Project
The Federal District Water Commission (FDWC) was created in 1992, to develop a new water management strategy, to improve public allocation and administration of potable water, drainage and treatment and reuse of residual waters and to promote a new cultural awareness of water as a finite resource to be paid for. The decree provided for privatising or allocating management and operation contracts for water services.

The FDWC began operating in 1992, requesting bids from private firms for the management of water distribution and billing. Ten year contracts were signed with four winning firms, joint ventures of leading Mexican construction companies and international water utility firms (French and English), each strategically contributing their expertise and state-of-the-art technologies in water-related services. 1/ The firms are paid according to offered unit prices for agreed activities. All activities and corporate image is conducted in the name of the FDWC and all revenues for water services are given to the Treasury.

This was the beginning of the Mexico City Water Strategy Project. Its main objectives are to assure the physical and financial sustainability of the hydraulic systems and guarantee the provision of water for future generations, following strategies to achieve the modernisation of the water management structure, enforce metered service billing to reduce immoderate use of water, stabilise the local aquifer, procure more revenue and improve all water services.

Table of Contents

Brochure

International Year of Forests

World Environment Day

UNEP Campaign