The 'filthy, stinking' old water hole. Pic: WaterAid/Alex Macro
Earlier this month 12 UK water company employees visited Tanzania to see WaterAid's work there. They hope what they found out will raise awareness of the charity's achievements.
For decades, people have left their rural communities and migrated to Dar es Salaam, previously Tanzania's capital, hoping for a better life.
Many arrived with little or no money, establishing slums by the city's port, which remain a mass of ramshackle homes.
Among the neighbourhoods is the sun-bleached Zamcargo camp - less than a square mile in size and home to about 2,300 people.
It was here that WaterAid showed the 12 UK volunteers the clean water supply it had built to replace the muddy water hole which had previously served the community and was a source of disease.
"The water hole contains a natural spring but it was gut-wrenchingly disgusting - it really stank," said David Wood, 28.
"It was basically a big muddy hole with a bright green sludge at the bottom and that is where people got their water."
Before the work was carried out in 1999, Zamcargo women and girls used to make several trips a day to the hole, which is on the nearby beach - a muddy, litter-strewn expanse.
Cholera, diarrhoea and dysentery were rampant - human waste used to run into the hole from the slum, as did rubbish and oil.
Now, there are six tap points around the slum, feeding off an electric pump which provides fresh water. Twenty shillings (one penny) buys 20 litres, a price the vast majority can afford.
An attendant is employed to monitor the supply and the pump is heavily secured, even though the main problem comes from the power cuts which incapacitate the system rather than thieves.
The water supply has drastically reduced disease, said Mr Wood, from Manchester, who works for United Utilities in Warrington.
WaterAid has also built special eco-toilets in Zamcargo which produce fertilizer for villagers to sell.
Mr Wood also points to the benefits the scheme has brought to the community's children.
A safe water supply for Zamcargo. Pic: WaterAid/Alex Macro
Many used to spend their days trekking to and from water supplies, carrying huge containers, but can now go to school.
And their life is safer as youngsters carrying water in the slums were victims of attacks.
Liz Almond, from Reading, who works for Thames Water, said WaterAid's work had given residents a sense of ownership of their water supply.
Villagers formed committees to apply for water pumps and are involved in the whole process - including digging trenches for the pipes.
The volunteers also travelled to Lugala, near the capital Dodoma, where they helped make bricks and dig trenches for pipes.
Ms Almond, 32, said there is a real sense of pride in what has been achieved.
WaterAid's hygiene education programmes mean villagers take their shoes off near their pump, aware of the need to prevent contamination. Those who refuse are fined.
And children teach each other about sanitation - one method involves using a version of snakes and ladders, which graphically spells out safety rules.
"It's been an amazing trip," said Ms Almond. "The people have all been so happy and friendly and there have been many magic moments, such as meeting so many wonderful children.
"But what really had a massive impact on me was putting the first hand pump together in Unyianga.
"The water pump is iconic of WaterAid and it's quite incredible to think something so simple will have such an impact on peoples' lives."
It's a point Liz and her colleagues will make during their promotional work for WaterAid across Britain.