I was not even talking about using a specific measurement. Back in some earlier years when I was using water balloons, I couldn’t really measure because I had to put the balloons straight onto the sink faucet, fill, then let out a tiny amount to push out the air. I then had to struggle to get an equal amount into the other balloon.
I use a measuring cup and a funnel.
I also have a small “cooking” scale. I take a marker and write on my forms what they weigh to keep track if them. I have 5-6 sets if different sizes. I use CC’s or ML which works out nicely because one CC or ML of water weighs one gram. So I can write 1500 on my form and know it was 1500 CC of water and weights 1500 grams.