I went hiking in Joshua Tree last spring and thought I was drinking enough water. I had a full Nalgene, I was sipping regularly, I felt fine. By the time I noticed my mouth was dry and I had a headache, I was already dehydrated. The ranger at the visitor center told me: “If you feel thirsty, you have been dehydrated for at least an hour.”

He showed me a couple of quick checks that tell you where you stand before your body has to scream for water. I use them now whenever I am traveling, working outside, or just sitting at my desk for too long. Here is what to look for.

The skin pinch test (takes two seconds)

Pinch the skin on the back of your hand between two fingers and let it go. If it snaps back immediately, you are hydrated. If it takes a second or two to flatten out, or stays tented up for a moment, you are dehydrated.

This works because your skin’s elasticity depends on water content. When you are low on fluids, the skin loses that snap. Do this on the back of your hand, not your arm — the skin is thinner there and the response is faster. This is the same test nurses use on elderly patients, by the way. It is legit.

The urine color check (the gold standard)

Look at your urine. Pale straw or lemonade color = hydrated. Dark yellow or amber = drink water now. Brown or orange = serious dehydration, possibly medical attention.

One thing that trips people up: if you take a multivitamin or B-complex supplement, your urine will be bright yellow regardless of hydration. The excess B vitamins tint it. So if you take vitamins, do not rely on color alone. Combine it with the skin pinch.

Also: if you are peeing less than four times a day, you are almost certainly not drinking enough. Six to seven times is normal for a well-hydrated adult.

The other sneaky signs

Bad breath. When you are dehydrated, your body produces less saliva. Saliva has antibacterial properties, so without enough of it, bacteria multiply in your mouth and cause that stale taste and smell. If your breath is bad even though you brushed, try drinking a full glass of water first before reaching for gum.

Sugar cravings. Dehydration makes it harder for your liver to release glycogen (stored glucose). Your body interprets that as needing quick energy and sends sugar cravings. If you suddenly want a candy bar at 3 PM, drink a glass of water and wait ten minutes. Half the time the craving goes away.

Feeling cold when others do not. Water helps regulate body temperature. When you are dehydrated, your body struggles to maintain a steady temp and you might feel chilly in a room where everyone else is comfortable.