How Do the Kidneys Maintain Water Balance in the Body

How Do the Kidneys Maintain Water Balance in the Body

We all know how important it is to drink enough water on a daily basis. Still, have you ever wondered what happens behind the scenes? Too much or too little water may cause issues that can have permanent consequences if not addressed on time. In addition to other organs, the renal system plays a significant role in regulating this equilibrium. But how do the kidneys maintain water balance in the body? 

In the following post, we’ll take a closer look at our anatomy, especially the urinary system and the ways it contributes to fluid balance. We’ll also share some useful tips and tricks that can help you track your water intake for optimal results.

Maintaining Water Balance: How Does It Work?

While the kidneys play an integral role in regulating fluid composition, they’re not the only ones responsible. Namely, the water balance in our bodies is also maintained by the following organs:

  • Mouth — Produces saliva to commence digestion
  • Skin — Prevents water from evaporating 
  • Liver — Helps remove toxins
  • Small intestine — Absorbs water and nutrients

Fluid Balance and the Kidneys

We’re sure you remember some of these facts from your biology class, but let’s refresh your memory just in case. Namely, the kidneys are part of the urinary system, which is in charge of removing the excess water, urea, and salts from our bodies. Simple enough, isn’t it? But how do the kidneys regulate fluid level? This is where things get a bit more complicated.

How Do the Kidneys Maintain Water Balance in the Body


Whenever we decide to intake any fluids, our bodies regulate their overall amount through urination, defecation, sweating, and, to a lesser extent, breathing. Fluid balance is directly affected by a process called osmoregulation. Considering that we’re 50–75% made of water, our organs and tissues are practically drenched in liquids at a certain pH, temperature, and solute concentration. Osmoregulation entails maintaining the concentrations of these solutes at an optimal level.

At this point, you might be wondering — when do the kidneys come into the picture? Well, these organs are actually the ones in charge of osmoregulation. In other words, the kidneys control bodily fluid volume through the amount of water excreted in the urine.

The kidneys contain millions of filtering units called nephrons, each containing a kidney tubule. When our blood passes to nephrons through capillaries, it enters at high pressure aiding the process of filtration. Afterward, the molecules that manage to pass through the nephrons include glucose, urea, water, and ions. The kidneys then reabsorb the needed molecules, and the rest passes through urine.

Optimal Water Balance: Tips and Tricks

Now that you know the answer to the age-old question — “How do kidneys regulate fluid level?” —  it’s time to move on to more pressing matters. How many times has the day gone by without you drinking the recommended amount of water? In fact, before we continue, we urge you to fill up your glass and have a sip. Go on, we’ll wait. 

How Do the Kidneys Maintain Water Balance in the Body

Okay, now that is out of the way, we have prepared a few handy tips and tricks to help you up your water intake so your kidneys can take over and do their job. 


  • Make sure to keep a glass of water within reach at all times.
  • Buy that reusable bottle from your wishlist and carry it with you whenever you’re out and about.
  • Use a smart scale like Eros to keep track of your body water levels.
  • Spice things up a bit by adding fruit or herbs to your water for more flavor. 
  • Establish a routine of drinking water as soon as you wake up.
  • Do a fun challenge with your friends to see who’ll be the most successful water drinker.

EROS Smart Scale

EROS Smart Scale

Bottom Line

Maintaining optimal levels of hydration is essential for healthy physiological and mental performance. In fact, every cell of our body requires water. Kidneys are the biggest contributors to maintaining optimal fluid balance in the body. These organs help remove excess nutrients and waste from our system and control the volume of fluids and the concentration of electrolytes. With this knowledge, you can now work to ensure normal water levels at all times. Don’t wait to become thirsty, as this is already a sign of dehydration. Instead, fill up that water bottle you have lying around and make sure to drink at least 2 liters daily. Stay hydrated!