More than 1.4 million Gaza Palestinians are facing an impending health disaster from decaying sewage and water systems that lack vital spare parts, fuel, and maintenance work, due to an Israeli economic siege on the Gaza Strip.

"We are a one-generator-failure away from disaster," Michael Bailey, an Oxfam spokesman, told the Middle East Times.

"The situation is verging on critical. There are 35 sewage pumping stations operational in Gaza. If one of the pumps breaks there is no way to replace it, because of a lack of spare parts," said Bailey, whose organization works with Gaza's Coastal Municipalities Water Utilities. "This would mean sewage backing into homes and onto the streets and the resulting health problems associated with it."

In March an earth embankment around a sewage reservoir in the northern Gaza Strip collapsed spewing a river of waste and mud that killed at least five people.

Since July, the CMWU which maintains the majority of water and waste water networks, pumping stations, and water wells in the Gaza Strip, has been unable to perform normal functions because it does not have spare parts.

The World Bank and UNICEF have reported that despite repeated requests Israel has forbidden the importation by any means -- sea, air, or by land across the Egyptian border -- of consignments of pumps, metal pipes, air and oil filters, and other goods that need to be obtained from outside Gaza; while allowing only a few basics to be trucked through the Erez crossing with Israel in the northern Gaza Strip.

"We are worried about how we will cope with a flood from sewage pump stations, water shortages, and other problems, because we know that we don't have the materials to respond to urgent needs. We are unable to make the necessary repairs or carry out preventative maintenance, Monther Shoblak, CMWU's general manager told the Middle East Times.

Israeli Defense Forces spokesman Col. Nir Press disputed this claim, saying that in early December Israel had permitted the delivery of 4,500 tons of essential medicines and spare parts in a convoy of 106 trucks, but that attacks from Gaza disrupted plans.

"We are operating under a situation where the crossing points to Gaza, through which aid is delivered, come under regular rocket and Qassem [home-made rockets] attacks from militant groups, thereby forcing us to strike a balance between delivery and security," he told the Middle East Times.

Water and sewage pumps in Gaza run on electricity. When there is not enough, they run on standby generators, which are powered by fuel. The interruption of both electricity and fuel supplies has at times forced water and sewage pumps to stop operating altogether.

The CMWU operates some 130 water wells, 33 sewage pump stations, and three treatment plants. Ten of the wells run on fuel, and the others on electricity. Diesel-powered generators are used as a back-up system in the event of electricity disruptions.

The company said it presently receives only half the amount of fuel needed to operate its wells, pumping stations and treatment plants 24 hours a day.

After Hamas took over the Gaza Strip in a military coup in June last year Israel bombed Gaza's main power plant and imposed a blockade on Gaza.

Following continued Qassem attacks on Israeli towns bordering Gaza, supplies were further reduced in October -- diesel by 49 percent, petrol by 40 percent and industrial diesel by 14 percent -- according to WHO.

Bailey argues that the civilian population is being unfairly punished for crimes they never committed, in contravention of international humanitarian law.

"We have tried unsuccessfully to persuade the Israeli authorities that importing these parts and resuming the supply of urgently needed fuel is an essential part of humanitarian aid, just as are basic foodstuffs which are permitted to enter," he said.

Since May, 149 public wells in Gaza have had too little fuel to operate and have not been maintained due to the lack of parts.

As a result 15 percent of Gaza's population -- 225,000 people -- get water for only two hours per day. Gaza has an annual population growth rate of 3.6 percent and the water extracted from the coastal aquifer is not being replenished.

Furthermore, the poor quality water has not been tested for more than a year, because laboratories have been unable to import chemicals to test it. WHO tests carried out several years ago concluded that Gaza's water is unfit for human consumption.

The seriousness of the situation prompted ex-British premier and current Quartet envoy, Tony Blair, to get involved in the World Bank's North Gaza Emergency Waste Water Treatment Project and use his influence and clout to persuade the Israeli authorities to allow in urgent spare parts for this particular project.

But Shoblak claimed that this was not enough for the remaining treatment plants in Gaza and said that the Israelis were still refusing to allow in the delivery of essential supplies.