Information on the Rainsoft 9591 reverse osmosis drinking water system can be found here:
http://www.waterfilters.net/Rainsoft...m_p_0-902.html
The first stage of the Rainsoft 9591 RO system can be replaced by the Pentek P5 sediment filter:
http://www.waterfilters.net/culligan...filters/P5.htm
The second stage of the Rainsoft 9591 RO system can be replaced by the Pentek EPM-10 carbon filter. The Pentek EPM-10 can be found here:
http://www.waterfilters.net/Pentek/w...ers/EPM-10.htm
The replacement filter for the third stage of the Rainsoft 9591 RO system is the CTA-RS9-10. The Rainsoft CTA-RS9-12 reverse osmosis membrane can be found here:
http://www.waterfilters.net/Rainsoft...e_p_0-581.html
The thrid stage of the Rainsoft 9591 reverse osmosis system can be replaced by the Omnipure CL6ROT33-B granular activated carbon water filter. The Omnipure CL6ROT33-B post filter can be found here:
http://www.waterfilters.net/Omnipure...r_p_0-754.html