Clean drinking water takes massive state investment, which will only be provided in a society where a) the government is truly accountable to the people and b) the government has sufficient tax revenues or a way of charging people fairly for the water. The benefit to society is reduced mortality and reduced illness, particularly among children.
Could it be that obtaining back handers from profitable mobile phone companies is a more important priority for the Philippine government than investing precious resources in something which will not make a profit?