# RV Waste Water Tank Repair in Chino > We repair cracked gray and black holding tanks, replace failed dump valves, and fix the sensors and venting that cause smells and bad readings, all in our Yorba Linda shop. The waste side of an RV is the gray tank from your sinks and shower and the black tank from the toilet, plus the gate valves, drain lines, sensors, and roof vent that tie them together. When a tank cracks, a dump valve will not seal, or the bathroom smells no matter what you do, OCRV Center repairs it in shop. This is dirty, below-floor work, and doing it on a lift with the underbelly open is the only way to get a clean, lasting result. ## Tank repair and replacement Holding tanks are roto-molded polyethylene, which is tough but cracks at stress points: a mounting strap that worked loose on rough road, a tank that was overfilled and froze, or an impact from low clearance. Welding polyethylene is a specific process, not a quick patch, and a tank patched with the wrong material simply reopens. We drop the tank, clean and dry it fully, and either plastic-weld the crack or replace the tank when the damage is past repair. Access is the real job. Many coaches bury the tanks behind a coroplast underbelly, insulation, and a tangle of plumbing. We open the underbelly properly, support the tank, and reseal everything when the repair is done so road spray and rodents stay out. - Plastic welding of cracked polyethylene gray and black tanks - Full tank replacement when a crack is past repair - Tank strap, hanger, and mounting bracket replacement - Underbelly and coroplast removal and proper reseal - Flush-system and tank-rinser fitment ## Gate valves, fittings, and drain lines The number one waste complaint we see is a dump valve that will not seal, so a tank weeps into the bay or onto the ground. The blade valve has a seal that hardens and tears, and the fix is replacing the valve and its seals, not forcing the handle. We replace the gate valves, the rotted ABS fittings around them, and any drain line that has gone brittle. We also reroute and rebuild sloppy drain plumbing that traps waste and breeds odor. Lines that sag or run uphill never fully drain, which is a constant source of smell and clogs. We set proper fall toward the dump outlet so the tanks actually empty. - Black and gray gate (dump) valve and seal replacement - ABS drain line, P-trap, and fitting repair and rerouting - Dump outlet, bayonet cap, and sewer-hose fitting replacement - Macerator pump repair and replacement where fitted - Proper drain slope correction so tanks fully empty ## Sensors, venting, and odor control Tank level sensors that read full when the tank is empty are almost universal, and the cause is usually waste film bridging the probes rather than a dead sensor. We clean or replace the sensors and, where it makes sense, fit external sensor strips that do not foul. We will tell you honestly which sensor problems are worth chasing and which are cosmetic. Persistent bathroom odor is usually a venting problem, not a tank that needs more chemical. A blocked or poorly placed roof vent lets gas back up into the coach, and a dry toilet seal lets black tank air straight into the bathroom. We clear and correct the vent stack, replace the toilet flange seal, and confirm the system breathes the way it should. - Tank level sensor cleaning, replacement, or external sensor fitment - Roof vent stack clearing and vent cap replacement - Toilet flange seal replacement to stop black tank odor - Anti-siphon and air-admittance valve service - Full leak and odor test before the coach leaves ## Frequently asked questions ### My dump valve leaks every time the tank fills. Is the whole tank bad? Usually not. A weeping dump valve is almost always a worn gate valve seal, not a failed tank. We replace the valve and seals and check the fittings around it. We only talk tank replacement if the tank itself is cracked. ### Can a cracked black or gray tank actually be repaired, or does it need replacing? Many cracks can be plastic-welded once the tank is dropped, cleaned, and dried, and that holds well. If the crack is at a stress point that will reopen or the tank is brittle with age, we recommend replacement and tell you why. ### My tank sensors say full but I just dumped. Can you fix the readings? Yes, and it is one of the most common things we see. The probes are usually bridged by waste film, not broken. We clean or replace the sensors, and on some coaches we fit external sensor strips that do not foul the same way. --- Source: https://oc-rv.com/services/waste-water-tank-repair/ OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. Phone (949) 799-3387. In shop only; insurance billed direct.