I see you used sewage outlet = 17500, and water intake 15000. I would love to know why this works. I have been search around the wiki and modding forums for any real explination of the set of water and sewage properties and can't find any at all. Have you seen any?
I just cant get my head around those figures clean sewage on the face of it it looks like more sewage is being generated than being taken in - but i am sure that's not how these figues are read!!!
your description says
240,000 units of water recycled per week
280,000 units of water treated per week
(I get the converstion values they are in the wiki)
where did you get that water intake = recycled per week and sewage outlet = water treated ?

any explanations much appreciated :-)