Always flush. I have a septic tank and if you don't make sure to run some minimum amount of water into it, it'll get crusty and start to have clog problems. As long as we're running water though it's great for 8-10 years between pumps.
Better to just run more water when possible.

Also it's nasty if someone goes to take a dump and there's piss chilling in there. If you get hit with Posideon's kiss it's gonna be double nasty. So you flush it before doing your business and now the net effect is zero anyway, wasting the effort. Blech.

Flush every time. Piss stinks and leaving it in the toilet causes those nasty water-level rings of scum on the toilet bowl. Fucking disgusting.

Grew up on a farm with limited water. Flush a shit, always, and piss only after it started to smell.

Fast forward 20yrs, living in town, have a family and we still do the same.

Water is a valuable resource everywhere; a bit of piss in the dunny really isn't a big deal.

I live in a desert and have my water trucked in every 3 weeks at significant cost.

Flush every time. Piss smells.

Always flush. I don’t want to drop a log and have that piss water splash on to me. Not to mention that it just stains the bowl and sometimes smells. Just flush, cause if I see it’s not clear water, I’m going to flush anyway.

Increasing water efficiency is likely to result in reduced demand for water, with less water therefore flowing through drains and sewers. Some parties have suggested that this could lead to blockages, drainage problems and homes flooding due to backed up sewerage systems.

In Germany our toilets usually have two buttons, one for the yellow which flushes but with a lower amount of water and the bigger button for the big brown business and maximum water flow.

Depending where you live and depending on drought being a thing in your place of the world, using less water can have unwanted side effects:

• backed sewerage systems
• not enough water can lead to environmental problems if the sewage isn't watered down enough for your sewage treatment plant to deal with it or if it goes straight to a river it is worse than with more water (that one is always really bad but definitely extremely worse with less water)

Allways flush, leaving pee in the bowl will cause stains and make it look disgusting

Just flush the toilet. Get a water efficient toilet if need be, problem solved

Why is your piss yellow and smells? That would be my bigger concern

The more it mellows, the more it smells, especially if you have a healthy diet. The person following has to deal with that smell which worsens the moment the water is agitated.

It's also a breeding ground, so you'll be cleaning much more frequently.

Only if your city has directed saving water in a drought scenario should you be not flushing your waste.

Everyone saying that piss stinks really need to be drinking more water #Hydro Homies

If I'm living solo, sure, I'll let it mellow, but never brown. If others are around, I never mellow, as a courtesy.

I only see one argument for not flushing urine, and that's for the environmental impact. However, you also must consider that not flushing urine will force you to clean the toilet more often as urine will stain the sides of the bowl. Without a detailed analysis we can't know which one is worse for the environment, but personally I will always flush.

It takes next to no effort to flush and it keeps the bathroom cleaner.

When the house is sleeping, let it mellow quietly.

When everyone is awake flush, every time.

If you don't immediately throw someone who doesn't flush off of your property to never return, you're nasty too.

Flush. Your basic water usage is absolutely miniscule compared to what major companies use. I'll start not-flushing the day they start doing things to minimize their own water waste. I'm taking my hour-long hot shower, too.

Piss in the sink. Wash hands. Problem solved!

I went through a period where I was under doctor's orders to treat any fluid produced by my body as a biohazard. That meant any time I urinated I had to close the lid and flush twice. So yeah, there was no mellowing in that case.

Whoever came up with "if it's yellow let it mellow" is a disgusting person. Piss smells. Yes, yours too. Flush the damn toilet!

It fucking smells after a few hours. If you have more than one toilet in your house, this can be a real issue if you invite people over.

The more I flush the more water I use.

The more water I use the less money I have.

The less money I have the more sad I am.

Just flush the fucking toilet. 😬