{"product_id":"promaster-undermount-grey-water-tank-clearance","title":"Promaster Undermount Grey Water Tank (Clearance)","description":"\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003eMounting a large capacity grey water tank underneath a Promaster van is a real challenge (we've been there). The \"cavities\" under the van are odd shapes and not very deep. So, we're very excited to offer this 26 gallon, custom molded grey water tank system that was designed specifically for the Promaster!\u003c\/p\u003e\n\u003ch2 class=\"wpb_heading wpb_singleimage_heading\"\u003eDimensions\u003c\/h2\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/promaster-grey-water-tank-dimensions_4f4e7aae-2c33-4388-816f-c0ceaa277c8d.jpg?v=1767368671\" alt=\"\"\u003e\u003c\/p\u003e\n\u003ch2 class=\"wpb_heading wpb_singleimage_heading\"\u003eLocation Of Tank Under Van\u003c\/h2\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/Promaster-Underbelly-1024x665.png?v=1767368645\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg\u003e\u003cimg\u003e\u003cimg\u003e\u003cimg\u003e\u003cimg\u003e\u003cimg\u003e\u003cimg height=\"216\" width=\"288\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/grey-water-tank-for-promaster-van.jpg?v=1767368796\"\u003e \u003cimg height=\"147\" width=\"291\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/custom-molded-water-tank-for-promaster-van_bffbcff8-6ce0-4af5-8e01-ad22d6bcfc53.jpg?v=1767368796\"\u003e \u003cimg height=\"218\" width=\"291\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/breather-valve.jpg?v=1767368796\"\u003e \u003cimg height=\"218\" width=\"291\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/functional-not-beautiful.jpg?v=1767368795\"\u003e \u003cimg height=\"157\" width=\"292\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/promaster-shower-drain-grey-water-tank-plumbing-scaled.jpg?v=1767368796\"\u003e \u003cimg height=\"160\" width=\"294\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/motorized-dump-valve-promaster-van.jpg?v=1767368795\"\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eOn older Promasters, you might find a bracket near the rear of the tank location that needs to be cut off prior to installation of the tank. Below is a photo of the tank positioned under a Promaster showing the bracket. We recommend using an angle grinder with a cut-off wheel to remove it and then grind it flat so that there are not any rough\/sharp edges that might cut into the tank plastic.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cimg height=\"282\" width=\"410\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/bracket-to-cut-off.png?v=1767368937\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cmeta charset=\"utf-8\"\u003eCustomer Nick H. (installed photo below) says: \u003cem\u003e“Wanted to let ya know the tank arrived and is dyn-no-mite! Huge thank you to Tiffany for her attention to detail and patience with my back \u0026amp; forth questions, Mike for helping me with photos showing the real estate around inlet location 1, and Zach for the install video which I watched more times that I care to admit.  \u003c\/em\u003e\u003cem\u003eInstall was straightforward and the directions perfectly organized!”\u003c\/em\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cem\u003e\u003cimg height=\"271\" width=\"361\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/greywater-tank-nick-h-rotated.jpg?v=1767368960\"\u003e \u003cimg height=\"482\" width=\"362\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/promaster-grey-tanks-brackets-e1761233950334.jpg?v=1767368960\"\u003e\u003c\/em\u003e\u003c\/span\u003e\u003cspan\u003e\u003cem\u003e\u003c\/em\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2\u003eHighlights\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eHolds approximately \u003cstrong\u003e26 gallons\u003c\/strong\u003e of grey water while virtually disappearing underneath the van and maintaining the ground clearance of the vehicle.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComplete kit\u003c\/strong\u003e comes with everything you need for the install including the tank itself, heavy duty steel mounting brackets, stainless steel attachment hardware and your choice of dump valve.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMounts underneath the passenger side slider door\u003c\/strong\u003e (see illustration for details).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eYour choice of dump valve\u003c\/strong\u003e is included (more details below).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeavy duty, 1\/8\" zinc plated (electro-galvanized) steel mounting brackets\u003c\/strong\u003e use existing holes in the structural members of the van to accept provided rivnuts - only one new\/additional hole must be drilled. The brackets come unpainted. We recommend that you paint your brackets to prevent corrosion. (The metal used to make the brackets is zinc plated (electro-galvanized) but during the fabrication process, the cut edges lose their protective coating). We recommend painting these brackets but we also offer a black, powder coated version as an upgrade.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCustom molded\u003c\/strong\u003e from medium-density polyethylene (MDPE). Polyethylene does not contain BPA and is FDA compliant for drinking water which means these can be used to hold drinking water.\u003c\/li\u003e\n\u003cli\u003eEach of the \"high points\" on the tank have a 1\/8\" \u003cstrong\u003ebrass breather vent\u003c\/strong\u003e to allow the tank to fill completely. \u003cem\u003eThese breather vents are not adequate for venting your drain lines\/tank. They are only for allowing the high point so of the tank to fill up and to provide a overflow mechanism.\u003c\/em\u003e Please see the \"venting\" section below.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSeem Expensive?\u003c\/strong\u003e\u003cbr\u003eWe understand this might seem expensive but it's a custom molded tank that is produced in small batches for a pretty niche market. Also, consider the costs of using an 0ff-the-shelf grey water tank as outlined below.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e$182 for an off-the-shelf grey tank. There are not many grey water tanks that can fit under the Promaster and hold about 26 gallons. The \u003ca class=\"\" title=\"\" href=\"https:\/\/www.ebay.com\/itm\/233095760456?epid=1422660699\u0026amp;hash=item3645970a48:g:dg4AAOSwi3xcPhms\" rel=\"noopener\" target=\"_blank\"\u003eone Zach used in his first three vans\u003c\/a\u003e works alright but it is taller than our custom tank so it eats into the ground clearance more and you can see it from the side of the van.\u003c\/li\u003e\n\u003cli\u003e$20 for a \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3wuZtgu\" rel=\"noopener\" target=\"_blank\"\u003egate-style dump valve\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003eIn 2019 Zach spent about $85 on the hardware to mount the tank under the van (angle brackets, bolts, nuts, etc.). Plus he had paint that all black and struggle under the van for much longer than was comfortable.\u003c\/li\u003e\n\u003cli\u003e$25 for miscellaneous PVC parts\/glue\/etc.\u003c\/li\u003e\n\u003cli\u003eShipping can vary depending on where you source all these parts but let's assume that it costs you $20 in shipping or gas driving to the hardware store.\u003c\/li\u003e\n\u003cli\u003eThis totals $352 in baseline costs. In addition to that, you're going to spend a lot more time and, ultimately, if you want a large capacity tank, it's going to \"hang down\" lower than this custom molded tank.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhy did we put this on the passenger side of the van when most RVs have the tank dump on the driver side?\u003c\/strong\u003e Primarily because the driver side cavities under the van on a Promaster are even smaller on the driver side because of the exhaust system. We wanted the highest capacity possible without compromising ground clearance.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eInstallation\/Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe tank ships as part of a complete kit to assist for simple installation. The only things you'll need that are not included in the box are clear silicone sealant and a rivnut tool, we recommend \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3OkJaLK\" rel=\"noopener\" target=\"_blank\"\u003ethis tool\u003c\/a\u003e if you can afford it and will be using rivnuts throughout your build but there are also more affordable options \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3tCNGuF\" rel=\"noopener\" target=\"_blank\"\u003esuch as this one\u003c\/a\u003e, to install rivnuts which are used with supplied bolts to secure the tank\/brackets to the van. There are 3x brackets (front, middle and rear). Each bracket has two bolt locations (one on each side of the bracket) for a total of 6x bolts. 4x of the supplied rivnuts can be installed into \u003cem\u003eexisting\u003c\/em\u003e holes underneath the van in the floor structure. One of those existing holes must be enlarged. One of the bolt locations has a factory threaded insert (M8). The final bolt location requires you to mark and drill a 7\/16\" hole for last supplied rivnut.\u003c\/p\u003e\n\u003cp\u003eOne the tank is mounted, you'll need connect the \"dump valve assembly\" to the 3\" outlet. We recommend you coat the outlet with clear silicone, insert the dump valve assembly and then tighten on the included 3.5\" hose clamp to secure the assembly.\u003c\/p\u003e\n\u003cp\u003eThe last step would be to plumb your drain lines into the 1-1\/2\" female NPT inlet. \u003cem\u003eNote that you determine the location of this inlet during ordering\u003c\/em\u003e. You can use various tee fittings to allow more than one fixture to drain into the tank.\u003c\/p\u003e\n\u003cp\u003eThere are 1\/8” brass breather vents at the top of each of the high points of the tank to allow the tank to fill completely in these areas. If the tank is overfilled these will also allow small amounts of gray water to escape the tank onto the ground. Please be careful not to overfill the tank. Overfilling the tank may result in gray water backing up into your fixtures or vent system. We highly recommend using some kind of tank monitoring system. Note, these small vents are \u003cem\u003enot\u003c\/em\u003e adequate for venting your drains, more information on that below.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e2023 or Newer Models\u003c\/strong\u003e\u003cbr\u003eRAM made a change to the angle\/geometry of the undercarriage structure of the Promasters starting with the 2023 model year. This creates an approximately 1\" offset between the rear bracket and the mounting hole at what we label \"hole location #2\" in the installation guide. So, for newer Promasters we include an aluminum spacer and longer bolt for this location.\u003c\/p\u003e\n\u003ch3\u003eVenting\u003c\/h3\u003e\n\u003cp\u003eIn order for your drains to work correctly (drain well and not too slowly) and to allow for fast emptying of the tank when it's full, you'll need to provide adequate venting for the tank and your drains. We discuss this a bit in our \u003ca class=\"\" title=\"\" href=\"https:\/\/www.vanlifeoutfitters.com\/camper-van-drains-and-grey-tank-plumbing-overview-video\/\" rel=\"noopener\" target=\"_blank\"\u003eplumbing video\u003c\/a\u003e. We recommend adding a vent to each drain\/inlet you have on your tank. You can also connect multiple drains to a single inlet that shares a vent if it works in your layout. Venting can be accomplished in many ways. Some installers will tee off a drain line (below the highest water level) and run this to a vent location. Others will dedicate a vent line to the tank with its own inlet. Similarly, vents can be routed a variety of ways such as to the sidewall of your van using something like a \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3eyRSXL\" rel=\"noopener\" target=\"_blank\"\u003ehorseshoe vent cover\u003c\/a\u003e or through the roof with a \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3TaDzr8\" rel=\"noopener\" target=\"_blank\"\u003eroof vent cover\u003c\/a\u003e. In some cases, such as for galley sinks, an \"\u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3Sh6OHS\" rel=\"noopener\" target=\"_blank\"\u003eair admittance valve\u003c\/a\u003e\" but those are not adequate for shower drains in my experience.\u003c\/p\u003e\n\u003ch3\u003eYour Choice of Dump Valve\u003c\/h3\u003e\n\u003cp\u003eWe offer three choices for emptying the tank. All three options are installed into the 3\" dump port that is built into passenger side rear of the tank.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eOption 1: Standard 3\" Dump Valve\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg class=\"alignleft wp-image-39412 size-medium hoverZoomLink\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/IMG_20220819_142806-300x225.jpg\" alt=\"\" width=\"300\" height=\"225\"\u003e\u003c\/p\u003e\n\u003cp\u003eThis is included in the base price and allows you to empty your tank using a \u003ca class=\"\" title=\"\" href=\"https:\/\/amzn.to\/3c5AJnh\" rel=\"noopener\" target=\"_blank\"\u003estandard RV-style sewer hose\u003c\/a\u003e. Because of of the large, 3\" opening, the tank empties quickly. The dump valve assembly we include comes out from the tank toward the sidewall of the van for easy access to the gate valve. You see this valve assembly from the side of the vehicle but it does not hang down exceptionally low or stand out. See photos in the image gallery.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eOption 2: Motorized (12 volt) 3\" Dump Valve\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg class=\"alignleft size-medium wp-image-39413 hoverZoomLink\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/IMG_20220819_142942-300x225.jpg\" alt=\"\" width=\"300\" height=\"225\"\u003e\u003c\/p\u003e\n\u003cp\u003eThis upgrade is the same type of 3\" dump valve that works with RV-style sewer hoses but is motorized and includes a remote panel\/switch for opening\/closing the valve. This is the most expensive and premium option. Like the standard dump valve, when installed, it will be positioned near and visible from the passenger side of the van for access to attach a sewer hose.\u003c\/p\u003e\n\u003cp\u003e\u003cimg class=\"alignnone wp-image-39416 size-medium hoverZoomLink\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/valterra-motorized-valve-panel-300x275.jpg\" alt=\"\" width=\"300\" height=\"275\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cbr\u003eOption 3: Motorized (12 volt) 3\/4\" Ball Valve\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg class=\"alignleft size-medium wp-image-39411 hoverZoomLink\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/IMG_20220819_142623-300x225.jpg\" alt=\"\" width=\"300\" height=\"225\"\u003e\u003c\/p\u003e\n\u003cp\u003eIf you're looking for something that is a bit more \"stealth\" this may be a good choice for you. This valve assembly is smaller and not visible from the passenger side of the van. It installs into the same dump valve port on the passenger side of the van but doesn't extend out to the side of the van like the 3\" dump options. Since the outlet is only 3\/4\" emptying time will be slower. Also, instead of standard 3\" connection for a RV-style hose, this ball valve has a 3\/4\" female NTP connection on the dump side so you either need to dump directly on the ground (in a location that is suitable for this) or connect up a garden hose to direct the grey water into a drain location. Because this connection is near the tank itself under the van, if you are using a hose, it will be more difficult to access. \u003cem\u003eNote that this option adds a few inches of height to the drain location which means that the tank cannot empty fully. We offer the option of adding a 1\/2\" fitting onto the bottom of the tank, below the dump valve, with \u003ca class=\"\" title=\"\" href=\"https:\/\/www.vanlifeoutfitters.com\/wp-content\/uploads\/2024\/06\/half-inch-mini-ball-valve.jpg\" rel=\"noopener\" target=\"_blank\"\u003ean included \"mini\" valve\u003c\/a\u003e so that you can fully empty the tank when needed.\u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/drive.google.com\/file\/d\/1R1FLurgEbKYt2uIB-OhYIQN-JU9_UVC0\/view?usp=drive_link\"\u003ePDF Manual\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eYour Choice of Inlet(s) and Location(s)\u003c\/h3\u003e\n\u003cp\u003eWe included 1x, 1-1\/2\" female NTP inlet in your choice of seven standard locations (shown in the image below). If you have multiple drains, you can use a \"tee\" fitting to split this inlet or choose to have a second added to your tank at an additional cost.\u003c\/p\u003e\n\u003cp\u003eAll the fittings are spin welded.\u003c\/p\u003e\n\u003cp\u003e\u003cimg class=\"alignnone wp-image-39417 size-full\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/tank-inlet-locations.jpg\" alt=\"\" width=\"1800\" height=\"927\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eClick on image to see larger.\u003c\/em\u003e On older Promasters, you might find a bracket near the rear of the tank location that needs to be cut off prior to installation of the tank. Below is a photo of the tank positioned under a Promaster showing the bracket. We recommend using an angle grinder with a cut-off wheel to remove it and then grind it flat so that there are not any rough\/sharp edges that might cut into the tank plastic. Customer Nick H. (installed photo below) says: \u003cem\u003e\"Wanted to let ya know the tank arrived and is dyn-no-mite! Huge thank you to Tiffany for her attention to detail and patience with my back \u0026amp; forth questions, Mike for helping me with photos showing the real estate around inlet location 1, and Zach for the install video which I watched more times that I care to admit. \u003c\/em\u003e\u003cem\u003eInstall was straightforward and the directions perfectly organized!\"\u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003e\u003ciframe title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/qJqmsvF_QSs?si=2_tBG79ltVVCVlS6\" height=\"315\" width=\"560\"\u003e\u003c\/iframe\u003e\u003c\/em\u003e\u003c\/p\u003e","brand":"Vanlife Outfitters","offers":[{"title":"Default Title","offer_id":48711369392318,"sku":"VLO-PM-GREY1","price":379.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0713\/6359\/2382\/files\/444GreyWaterTank_1.jpg?v=1786637197","url":"https:\/\/www.vanlifeoutfitters.com\/products\/promaster-undermount-grey-water-tank-clearance","provider":"Vanlife Outfitters","version":"1.0","type":"link"}