Drinking plenty of water can help maintain optimal kidney function, this is common knowledge. However, no evidence is seen that promotes drinking water in managing proteinuria. Especially, in case of proteinuria due to kidney failure, water intake needs to be limited as per doctor's instructions.

Foodstuffs that are rich in sodium and phosphorus should be avoided if you have proteinuria and they include:
Whole-wheat bread or brown rice
Fruits such as avocados, bananas and oranges (juice)
Dairy
Canned foods
Dark-coloured colas

Yes, there are some ancient ayurvedic herbs which have proven to help to treat proteinuria.

Treatment of proteinuria depends on the treatment of the cause as it is not a specific disease. If left untreated, it has serious consequences such as kidney failure. Hence the treatment duration for proteinuria is variable. No treatment (temporary or mild cases) or extensive treatment as per the severity of the cause.

The medications used for the treatment of proteinuria are basically the drugs used to treat the underlying cause and include:
Angiotensin II receptor antagonists (ARAs)
Aldosterone antagonists, selective
ACE inhibitors
Calcium channel antagonists
Diuretics (loop, thiazide)