Discharge Controllers
Dometic/Sealand Holding Tank Discharge Controllers
Keeping your sanitation system compliant starts with the right discharge controller. Dometic/Sealand controllers manage when and how your holding tank empties, with automatic and manual options designed to prevent accidental overboard discharge. Whether you're upgrading your system or replacing a failed panel, you're in the right place.
Not sure which controller is right for your system? Call us at 1-800-522-2656, Monday through Friday, 8:00 AM to 4:30 PM.
Choosing the Right Controller
Discharge controllers aren't all interchangeable. The right one depends on your voltage, your level of automation, and your existing seacock setup. The DTD series controllers are designed to work with Dometic Tank Monitors like the DTM 04.
DTD01 Manual : (12V): Basic manual operation. You control when the tank discharge starts. It will automatically turn off when the connected DTM empties the tank.
DTD01A Auto: (12V and 24V): Automatic/manual with a keyed switch. This model will automatically discharge sewage overboard when the tank reaches mid-level, and the key is set to “auto” mode or when manually activated. This should only be used when in unrestricted waters. Prevent accidental discharge in restricted waters by setting to “manual.”
DTD02 and DTD02A are also available, which, along with a Seacock Interlock switch, prevent discharge pump operation if the overboard seacock is closed to protect the duckbill valves.
TMG Control Module: (38531036 is the Grady White version): This Tank Manager Control Module is specific to Grady White vessels and is the most common. If you have a Grady White with a Dometic sanitation system, this is the replacement module for your installation. Other builders, such as Viking and Princess, have slight variations on some models.
Seacock Interlock Switches : (Groco and Conbraco): These, when connected through the DTD, prevent the discharge pump from running when the seacock is closed—an important safeguard against pressurizing a closed system. Available in two versions, depending on your existing seacock brand.
Replacement Key : (TM4 and TMG): A replacement key for Tank Master 4, Tank Manager, and DTD panels.
Frequently Asked Questions
What's the difference between manual and automatic discharge controllers?
A manual controller requires you to activate discharge deliberately, giving you full control over when the tank empties. The tradeoff is that it relies on the operator to manage timing and location. An automatic controller monitors tank level and discharges on its own when conditions allow, reducing the risk of an overfull tank—but it requires correct setup and a reliable level sensor to work as intended.
Do I need a seacock interlock switch?
If your discharge pump can operate independently of your seacock position, an interlock switch is a smart addition. It prevents the pump from running against a closed seacock, which can damage the pump and create backpressure in the system.
How do I know if I need the Groco or Conbraco interlock?
It depends on your existing seacock brand and type. The triangle flange is different between brands. The Groco interlock is designed for Groco seacocks. The Conbraco interlock is designed for Conbraco seacocks. Sometimes you’ll see it labeled as Apollo. The valve handle normally has the brand label. If you're not sure, call us before ordering. These do not typically work with European-style seacocks, which don’t have the flange.
My DTD panel isn't responding. Is it the controller or something else?
Start by checking the key and fuse. If the panel powers up but won't discharge, the issue may be with the pump or float switch rather than the controller itself. Call us, and we can help you troubleshoot before you order a replacement.
Need Help?
Contact us or call 1-800-522-2656. Browse all Discharge Pumps, Level Monitors & Controllers, or visit Dometic/Sealand.
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