The open type sewers and the fact no treatment happens is part of the problem. The next being the abandonment of plastic bags, old tyres and a lot of other things that just don’t decompose. Result a sludge ridden waterway full of stagnant water that is not only a breeding ground for mosquito’s but a waterway that no longer functions. Why is flooding such a problem throughout the Philippines? same reason the waterways regardless if a concrete drain or a wide river garbage is disregarded into it in the same manner. It reaches a point where it snags on something and slowly these build up to a large amount of waste stuck in the river etc. which reduces water flow. End result flooding as poor maintenance and a high disregard of personal responsibility on keeping the waterways clear cause a cycle that often leads to death directly or indirectly. The flooding where people drown or mosquito’s breeding spreading Dengue and in some parts Malaria which have high death tolls. I have had Dengue twice myself and the first time there was a lot of fear in people around me that I would die due to the way it attacked my immune system it literally took me from healthy to unable to walk more than 10ft without having to lay back down. I was one of the lucky ones but I wonder how much more lucky I would have been if these breeding pits like the one in the photo didn’t exist.