This is me submerging/filling the jar w/tank water.
Here’s something that everyone can do to not only lower their water bill, but to waste less clean drinking water. First, you fill a jar or a jug with water (I just use water from the toilet) and submerge it in your toilet tank. Make sure that the jar or jug sits on the opposite side of the flushing mechanism so that it will not get in the way of any moving parts. This works in conserving water because the jar/jug displaces that amount of water every time the bowl is filled. This Youtube video suggests using a 1/2 gallon jug but that seems a little excessive as you may need to flush twice sometimes for it to do the job and that’s really not conserving any water. I personally use quart jars in my toilets and I think a quart is just right. This equals to one gallon of water saved for every four flushes. For a household the size of mine that equates to 1700+ gallons of water savings every single year. Wow!
Don’t mind the nasty toilet bowl, but this shows where I put the jar.