Conversation so far:
What was the Orangi Pilot Project by Akhtar Hameed Khan?
The Orangi poverty alleviation project was initiated by Khan as an NGO in 1980.
Why did Akhtar Hameed Khan start the Orangi Pilot Project?
The project initially focused on creating a system of underground sewers, using local materials and labour, and succeeded in laying hundreds of kilometres of drainage pipes along with auxiliary facilities.
Are there any other interesting aspects about this Akhtar Hameed Khan and Orangi Pilot Project article besidesdrainage pipes with auxiliary facilities?
By 1993, OPP had managed to provide low-cost sewers to more than 72,000 houses.
Why did Akhtar Hameed Khan start the OPP?
At that time, it was the largest of the city's approximately 650 low-income squatter settlements.
How long did the OPP project byAkhtar Hameed Khan run?
How many programs did the OPP project by Akhtar Hameed Khan diversify into
The project subsequently diversified into a number of programmes, including a people's financed and managed low-cost sanitation programme; a housing programme; a basic health and family planning programme
Was the OPP model by Akhtar Hameed Khan a sucess
The successful OPP model became an inspiration for other municipalities around the country.

Question: What other countries use it?
Self-contained rewrite: What other countries besides Orangi, Pakistan use the OPP model by Akhtar Hameed Khan?