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Sun-Mar's Model 511 Plus Ultra Low Flush Toilet - For Use With The Centrex Composting Toilet Systems

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  • The 511 Plus Ultra Low Flush Toilet is the low profile version of the 510+ toilet, designed for use with the Centrex 1000, Centrex 2000, and Centrex 3000 Central composting toilet systems by Sun-Mar. Multiple low flush toilets can be used with the centrex systems if necessary.

    The 511+ offers a low profile for use when extra height is needed to allow the toilet to gravity feed to the composting unit.

    Using about one pint per flush, these ultra low flush toilets provide all the advantages of a flush toilet while minimizing water usage. They are ideal for use with Sun-Mar Central Composting Systems, but can also be used with holding tanks, overloaded septic systems, and in RV's.

    A simple foot pedal flush opens the water valve and gate when pushed down, and fills the bowl with water when lifted. After flushing, a small amount of water is held in the toilet bowl which is sealed by a self-cleaning ball valve and teflon seal. Even gravity-fed water from a roof tank is sufficient to flush a 1 pint flush toilet. In winter they can be flushed manually using a container if necessary.

    The 511+ ultra low flush toilet has a regular sized toilet seat. For Sun-Mar installations, we recommend the 510+ as the unit of choice as it has the size and appearance of a "regular" toilet. They come complete, except for the required Floor flange, (purchased separately).


  • OffGridAndGreen is a veteran family-run business that cares about each and every one of our customers. We are dedicated to making sure your shopping experience is a positive one each and every time. We also happen to be the world's largest online distributor of eco-friendly toilets. NO ONE knows toilets like we do.

    Price - No one can beat us on price. We’ve negotiated with all our suppliers to have the lowest price available for YOU. And, if you happen to find a lower price elsewhere, we guarantee a price match with our Best Price Guarantee. You will never need to shop around for a better value for your composting and incinerating toilets anywhere else, guaranteed.

    Quality - We understand how important waste management can be in your everyday life. We hand-picked all our manufacturers to ensure that you get a quality item. All items are inspected before leaving our warehouses so we know that you’ll be happy with the product that arrives at your door.

    Service - Every customer is a part of our growing family. When you order from us, we have an open line of communication with you - we tell you when your package is getting ready for shipment, we message you when it’s being shipped and we even send you the tracking code so you know when it’ll arrive at your door. We respond to all e-mail inquiries within 12 hours because we care about you. We also have a team of technical experts that can help you with your questions.

    Safe & Secure Shopping - Our online site provides the best online experience for buying composting and incinerating toilets. Our online ordering system is safe and secure to protect your privacy every step of the way.

    If you have any questions, shoot us an e-mail at and we'll get back to you right away. Happy Shopping!

  • Order Confirmation:

    All orders will be confirmed via e-mail directly after you place your order. The confirmation means that we have received your order in our system and have pre-authorized your credit card for the purchase. After we receive your order we will automatically reach out to our warehouses to confirm that the product(s) are in stock and available for immediate shipment. If your product by chance is on back order or unavailable we will void the pre-authorization and contact to you via e-mail.  If your item(s) are available for immediate shipment (within 14 business days) we will process the charges and submit the order to the destination.

    Order Shipment:

    If your ordered product(s) are in stock, and we process final charges to your credit card, it will ship within fourteen business days from the date of your order.  Once the product(s) have left our warehouse, we will send tracking information to the e-mail you provide.  If you do not receive tracking information from us within fifteen business days of your order, feel free to follow up with us at


    Please carefully inspect the packaging and the contents of your delivery when they arrive, if you notice damage to your shipment, please make note of it when signing for delivery.  If your item(s) do arrived damaged, please send photos to and we will process an insurance claim on your behalf.

    Cancellations & Refunds:

    All orders cancelled after 48 hours are subject to a $20 administration fee.  If you order has shipped, it will be the responsibility of the buyer to return the product. Off Grid and Green will not be accountable for any shipping charges on returned items. 

    Off Grid and Green will accept returns on any order within 30 days of the original purchase so long as the product has not been used and can be returned in the original packaging.

    All returned orders will be charged a 15% restocking fee. Upon receiving and inspecting the returned product, Off Grid and Green will issue a refund for the full amount minus restocking/administration fees to the credit card used for the purchase only.

  • Off Grid and Green works very hard to ensure we deliver the best prices on the internet.  If you find another internet retailer offering lower prices,  within 6 months of your purchase, please let us know and we will refund the difference to your original payment.  We want you to feel absolutely sure that you are getting the best possible price for the products on this site. 

    To request a partial refund, simply contact us with a link to the product on our competitors site within 6 months from the date of purchase and we will process your credit accordingly.

    Our Price Guarantee has some limitations:

    • You must purchase the item from Off Grid and Green before applying for our Price Match Guarantee
    • Special promotions, like rebates and buy-one get-one-free offers are do not apply.
    • The product must be in stock on the competitors site
    • The competitor must be an online only store, and they may not have a physical retail location
    • The site cannot be a discounter or auction site (ie; Hayneedle, eBay, Wayfair, Overstock, etc..)
    • The competitor must be an Authorized Retailer for the product in question
    • The Price Match Guarantee includes the product price and the shipping cost, it excludes sales tax