How can you identify whether brackish water is too salty to drink?

Question

Sometimes there are sources of water which are slightly contaminated with salt, such as coastal wells or pools of rainwater in rocks near the coast, or water containers with pinhole leaks which have been stored in proximity to seawater (e.g. aging Dromedary bags in a kayak). In these cases, is the subjective taste adequate to warn me when water has become too salty to drink safely? Is there another means?

I find the following answer regarding the danger of drinking seawater to be compelling: here I would like to know at what point these issues become decisive and the water should be avoided.

Answer 1

Just taste it.

As in this answer, normal saline matches what you have in you at 9 grams of salt to a liter of water (this is 9 times as much as Gatorade).

If you ever try to drink the stuff, its way too salty to be enjoyable (and is normally given intravenously for dehydration). So if the salty water is too salty to drink, that means you shouldn't. Some salt is okay and even beneficial but too much or too little is a problem.