When it's hot outside, you're exercising or are outside a lot, you need to take extra care to drink enough water. As heat waves increase in frequency, it's important to your health to get enough electrolytes as well. While you can find them in sports drinks and supplements, they can also be found in certain foods. In addition to keeping you hydrated, they'll help you replenish minerals you sweat out during activity.

Some foods are hydrating and full of electrolytes and nutrients, which can help quench your thirst while keeping you healthy. They'll also go a long way in keeping you hydrated through the heat wave. We spoke with an expert to narrow down which foods you should keep stocked in your fridge and the key hydration benefits they provide.

Also, see how much water you're supposed to drink and why you should drink more of it, and get our expert electrolyte hacks to start using today.

How to tell if you're hydrated

Hydration needs vary based on your size, activity level and how much you sweat. Gabriela Barreto, a registered dietitian and sports nutritionist says there are two indicators of hydration level: your thirst and the color of your urine. "Drinking to thirst can be appropriate for most individuals to maintain their hydration levels and as for urine, you're looking for a pale yellow color," says Barreto. She says the only times you shouldn't be concerned about the color of your urine are during your first pee of the morning because it tends to be dark, or if you are taking vitamin B supplements, which make urine more likely to appear bright yellow.

Read more: Best Reusable Water Bottles

Barreto recommends that besides food and water, a hydration supplement such as Skratch can benefit individuals with active jobs and people who work out or spend a lot of time in the heat outdoors. "Utilizing a hydration product can be useful to increase your body's water stores," she says. "I recommend a hydration product with 300 to 500 milligrams of sodium and preferably about 20 grams of carbohydrates." Keep in mind an electrolyte drink without carbohydrates will help with rehydration, too, just not as efficiently. So make sure to read the labels first to choose the best option for your needs.

Which foods are most hydrating?

Most foods contain some amount of water, but it probably won't surprise you to learn that fruits and vegetables are at the top of the list.

To get the most out of these hydrating fruits and vegetables, make sure you follow standard dietary guidelines. Barreto says, "Dietary guidelines recommend two to three servings of fruit and three to four servings of vegetables for most adults." There are no specific guidelines for hydrating fruits and veggies, but by eating the daily recommended amount of produce you will be adding to your hydration, she says.

It is estimated that 20% to 30% of fluid needs can come from food, including fruits and veggies. By combining certain foods, you can boost your hydration. "When looking to adequately rehydrate, carbohydrates, fluid and sodium are key," says Barreto, adding, "Carbohydrates are important for optimizing water and sodium absorption in the body."

Watermelon and other melons

Watermelon isn't just a fruit that is synonymous with summer, it's also highly hydrating. It's made up of 92% water and has antioxidants, important nutrients like vitamins A and C, magnesium, fiber and lycopene (a pigment found in red, yellow or orange-colored fruits and vegetables). Other melons such as cantaloupe are also made up of 90% water and are a good source of potassium, folate, as well as vitamins A and C.

Barreto says one hydrating summer recipe to try is a cucumber and watermelon salad with lime, mint and salty feta. As previously mentioned, the sodium and carbohydrates will help the body easily absorb the water from the fruit. Barreto points out that for this reason, you'll also notice some sports dietitians recommend sprinkling some salt on your watermelon.

Cucumbers

Cucumbers are made up of 95% water and consist of vitamins like vitamin K, magnesium and potassium. This refreshing veggie can be easily added to salads, sandwiches, water or eaten on its own. Its high water content also makes it a low-calorie vegetable and is an ideal food to add to your diet if you're looking to lose weight and feel full longer.

Squash

This versatile vegetable does well as an addition to soups, stir-fries, salads and as a side. Popular summer squashes like zucchini are a good source of vitamin C, potassium and fiber and are made up of 94% water. The high water and fiber content will keep you full and hydrated for an extended period.

Strawberries

This popular summer fruit is full of antioxidants, vitamins and minerals like vitamin C, manganese and folate. It's an easy fruit to add into smoothies, yogurt, salads or eat on its own. Strawberries are made up of 91% water, making them the perfect fruit to quench your thirst and satisfy your sweet tooth.

Lettuce and other leafy greens

Make a salad out of lettuce and other greens like lettuce, watercress, spinach or bok choy, which have high water content and provide lots of vitamins and minerals. Lettuce consists of 96% water and has folate, fiber and vitamins K and A. Spinach is high in iron, folic acid, calcium and vitamins C and A. Watercress, meanwhile, provides 100% of the recommended dietary intake for vitamin K, which is an essential nutrient for blood clotting and maintaining healthy bones. Bok choy is abundant in vitamins K and C, which means any combination of these greens is guaranteed to provide you with a salad full of nutrients.

Citrus fruits

If you enjoy oranges, grapefruits, limes and other citrus fruits, then eat up. Citrus fruits tend to be made up of about 80% water, making them good options for hydration. They are also high in vitamin C and fiber and are good for supporting your immune system. They're even versatile enough to add to fruit salads, eat on their own, add to water or salads and even as a marinade for proteins, such as chicken or fish.