{"product_id":"dometic-kit-4000-tank-cap-oring","title":"Dometic 4000 Series Waste Tank Cap \u0026 O-Ring Seal - Fits 310, 311, 320, 321 Series - Part# 385250022","description":"\u003cdiv class=\"erp-pdp\"\u003e\n\n\u003cp\u003eThe Dometic 385250022 Waste Tank Cap with integrated O-Ring Seal is a critical replacement component for Dometic 300 and 4000 Series gravity discharge toilets. This cap secures the waste tank opening and creates a leak-proof seal to prevent odors and spills during travel. If your original cap is cracked, the seal is worn, or you're experiencing odor leaks from the waste tank, this genuine Dometic replacement restores proper function and sanitation.\u003c\/p\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated O-Ring Seal:\u003c\/strong\u003e Pre-installed rubber seal ensures leak-proof closure without separate gasket installation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable Construction:\u003c\/strong\u003e Engineered plastic cap withstands UV exposure, temperature extremes, and chemical exposure from waste tank treatments\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSecure Thread Design:\u003c\/strong\u003e Precision-molded threads provide tight, reliable connection to waste tank opening\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDirect OEM Replacement:\u003c\/strong\u003e Exact fit for Dometic 300 and 4000 Series gravity discharge toilet waste tanks\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEasy Installation:\u003c\/strong\u003e Simple screw-on design allows quick replacement without tools or special skills\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOdor Prevention:\u003c\/strong\u003e Properly sealing cap prevents waste tank odors from entering RV living space\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"table table-bordered table-sm\"\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePart Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e385250022\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eProduct Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eWaste Tank Cap with O-Ring Seal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eUV-Resistant Plastic with Rubber Seal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eThread Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eStandard Dometic Waste Tank Thread\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSeal Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eIntegrated O-Ring\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eColor\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBlack\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eCompatible Dometic Toilet Models\u003c\/h2\u003e\n\u003ctable class=\"table table-bordered table-sm\"\u003e\n\u003ctr\u003e\n\u003cth\u003eSeries\u003c\/th\u003e\n\u003cth\u003eCompatible Models\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e300 Series\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e310, 311, 320, 321 Gravity Discharge Toilets\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e4000 Series\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eVarious 4000 Series Gravity Discharge Models\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\n\u003ch3\u003eHow do I know if I need to replace my waste tank cap?\u003c\/h3\u003e\n\u003cp\u003eReplace your waste tank cap if you notice cracks in the plastic, a hardened or damaged O-ring seal, persistent odors coming from the waste tank area, or visible leaks around the cap threads. Even minor damage can compromise the seal and allow odors to escape.\u003c\/p\u003e\n\n\u003ch3\u003eDoes this cap fit both the 300 and 4000 Series toilets?\u003c\/h3\u003e\n\u003cp\u003eYes, the 385250022 cap is designed to fit Dometic 300 Series (models 310, 311, 320, 321) and 4000 Series gravity discharge toilets. Verify your toilet model number to ensure compatibility before ordering.\u003c\/p\u003e\n\n\u003ch3\u003eCan I replace just the O-ring, or do I need the entire cap?\u003c\/h3\u003e\n\u003cp\u003eThis part includes both the cap and integrated O-ring seal as a complete assembly. While some caps allow separate O-ring replacement, this design integrates the seal for improved reliability and easier installation. Replacing the complete assembly ensures proper sealing.\u003c\/p\u003e\n\n\u003ch3\u003eHow often should the waste tank cap be replaced?\u003c\/h3\u003e\n\u003cp\u003eReplace the waste tank cap when you notice seal degradation, cracks, or odor leaks. With proper care, a quality cap can last several years, but exposure to UV light, chemicals, and temperature extremes can accelerate wear. Inspect the cap and seal annually during routine RV maintenance.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Choose Elkhart RV Parts?\u003c\/h2\u003e\n\u003cp\u003eElkhart RV Parts specializes in hard-to-find Dometic RV toilet components like the 385250022 waste tank cap. Located in Elkhart, Indiana — the RV Capital of the World — we stock genuine OEM Dometic parts for fast shipping to RV owners nationwide. Our team understands Dometic sanitation systems and can help you identify the exact replacement parts you need. When you order from Elkhart RV Parts, you get authentic Dometic components backed by expert support and quick delivery.\u003c\/p\u003e\n\n\u003c\/div\u003e","brand":"Dometic","offers":[{"title":"Default Title","offer_id":48364215632024,"sku":"385250022","price":151.42,"currency_code":"USD","in_stock":true}],"url":"https:\/\/elkhartrvparts.com\/products\/dometic-kit-4000-tank-cap-oring","provider":"Elkhart RV Parts","version":"1.0","type":"link"}