I have a theory as to why Melamchi is getting delayed so much.
It's because there's a business that's thriving because of scarcity of water in Kathmandu. These are tankers that supply water to households. According to this source (I don't know about the source's credibility but you'll get an idead of what I'm saying),
"Private tankers supply 38 MLD (106 L/day) in a peak season (dry period), which become 10% of the total water demand and more than 50 % of the water supply by KUKL in dry period (Tanker Association, 2016)."
No. of private tankers operating in Kathmandu valley: 610. No. of tankers with KUKL: 27.
Now, I don't know how much a Tanker worth of water costs, so if anyone knows, maybe they can do the maths. I can assure you supplying 10% of KTM's water certainly won't be a small number.
hence, if Melamchi was to become functional, thesetankers and their owners will be out of business then and there.
You might ask "This doesn't make sense. Why are 610 tankers and a business more important than the entire population of Kathmandu?" Well, most of the investment in these tankers are from (yup, you guessd it) politicians and karyakartas associated with politics, most of them affiliated in one way or another largely to the ruling NCP, and to a somewhat lesser extent, the opposition NC.
Why does the media not talk about this? Well, media in our country is useless and equally corrupt. Even if someone will pick up this news, every media house will suddenly start investigating and sensationalising it as if they care. Then, when a few weeks have passed, and their pockets are filled satisfactorily, they' go silent again. (Need I give an example? 33 kg Sunkanda, Wide body Plane kanda, Syndicate Kanda should serve you as recent memories).