I use this:
https://www.amazon.com/SHURFLO-RV-10...s%2C195&sr=8-4
and this:
https://www.amazon.com/SHURflo-15500...X0QBQWXGXCTJWS
This was very easy to install, I just installed it behind the city water connection on my cougar. Water taste awesome and filters are easy to change.