Buy a toilet with a tank that holds more than 6 liters
Use an incandescent light bulb
Buy an oven that can get hot enough to cook a pizza properly (except when in self-cleaning mode when there is a locking mechanism preventing you from using the high temperature to actually cook)
Detect a radar signal someone is beaming into your car unsolicited
Unscramble a TV signal someone is beaming into your home unsolicited
More examples later — add your own in the comments. I’m pretty sure these are all unconstitutional prohibitions.
Polymath's Blog 
I wonder if these have ever been tested in court?
The one with the rain water is the best. It’s a federal offense to not allow rain water to flow down by capturing it. 😀
I already asked you for a reference for that one, as did Gorb — I already knew you can’t drain your property if some agency has declared that some “wetland” includes it, but it sounds like you are talking about something more general.
Thanks for the link on the other thread — doesn’t belong on this one because it is laws in some states, not a Federal law, therefore not unconstitutional.
Though maybe the radar detector thing is also only state laws; some state laws are so intrusive that they might be unconstitutional too, and outlawing passively detecting something is certainly more intrusive than outlawing actively collecting rainwater which when it seeps into the ground affects the water table which has an environmental impact on neighboring properties. So I’m sure the rainwater thing is constitutional but still not sure about the radar detectors.
The rainwater thing is the result of treaties between the several states. The treaties specifically deal with ownership of acre-feet of the major rivers in the US. They’re written really tightly to prevent upstream states from diverting the flow to the detriment of the downstream ones. Personal water catchment is collateral damage of those treaties. Wars are often fought over water rights, so this is honestly kind of par for the course.