I HAVE A HOUSE WITH A CRAWL SPACE, MY PROBLEM IS IT USED TO HAVE A SEPTIC TANK, BUT WAS CONVERTED OVER TO THE CITY SEWER SYSTEM. HE WENT FROM A 5 INCH DRAIN PIPE TO A 4 INCH PIPE LEADING TO THE FEED LINE.( PRETTY SHABBY, DON'T YOU THINK ?) ANYWAY, WHAT KIND OF PIPING( P.V.C. OR CAST IRON ) WOULD YOU SUGGEST I INSTALL TO THE 4 INCH ( WITCH IS 6' UNDERGROUND) TO MAKE EVERYTHING RUN THE SMOOTHEST, (NO PUN INTENDED) ? ANY REPLY WOULD BE HELPFUL THANK YOU TOM