Can Hot Tub Water Kill Grass? Explained

If you are one of those people who often use a hot tub, you must have wondered what is the best way to replace the water in it. One of the options that must have crossed your mind is pouring it on your lawn or using it for your plants and grass. However, hot tub water is not the same water that is used for drinking and showering. Therefore, it’s normal to ask: can hot tub water kill your grass? In this article, we’ll talk about that. So, let’s start!

Can Hot Tub Water Kill Grass? No, hot tub water will not kill grass, but it can harm the grass. However, if the tub water has high levels of chemicals like chlorine or is too salty, it can damage or kill the grass. Therefore, be sure to check the water’s pH and chemical levels before using it on your grass.

While it might seem like a good idea to spill this water into your yard, the chemicals and salts that are often present in the water can harm grass. Are you curious about the specifics and how to safely handle hot tub drainage? Keep reading to dive deeper into this topic!

Will Hot Tub Water Kill Grass? 

Hot Tub Water Damage Grass

While emptying hot tub water onto your grass for the first time might not completely kill the grass, it could damage it. If your hot tub uses saltwater or contains added chemicals like chlorine or bromine, the water can be more harmful and potentially may kill the grass. Here is what you need to know about that:

Chlorinated Hot Water

A chlorine level that exceeds 2 parts per million (ppm) in the soil might harm the grassroots. Most hot tubs have water with chlorine to keep it clean and safe for people. Without chlorine, bacteria and fungi could build up, leading to skin problems. That’s why it’s important to have chlorine in hot tubs and pools.

If water from your hot tub occasionally splashes onto your neighbor’s grass, it’s usually not a big concern. These minor splashes don’t carry enough chlorine to harm the grass. When mixed with water, chlorine can be okay for grass in small amounts. But if you splash a lot of water, it could be too much chlorine for the grass, which might damage it.

You should be careful if you’re thinking about draining the whole hot tub onto your grass. Its chlorine content should be less than 0.1 parts per million to pour hot tub water onto the grass safely. If the chlorine levels are higher, it’s better to drain the water towards the street or another safe area.

Related Article: What Is the Right Temperature For a Hot Tub?

Effect of the pH of Hot Water

The pH level of the water that comes out from a hot tub or pool can impact the pH of your yard’s soil. Most types of grass thrive in soil that is a bit on the alkaline side. To ensure your soil stays in good condition, the pH of the water from your hot tub should be between 7.0 and 7.8.

If the water is more acidic, it can also make your soil acidic. This isn’t good for the grass and can even cause it to struggle or die. To find out the pH of your pool or tub water, you can easily test it. Just use a pH strip and compare the color to the provided chart to determine the pH level of your water.

Effect of Salt

Saltwater isn’t good for plants or grass. It can hang around in the ground for quite a while. When there’s too much salt in the soil, it pulls water away from the roots of the grass, causing them to dry out. Over time, this can hurt the grass a lot.

That’s because the salt messes with the soil’s pH. When that happens, the grass has difficulty getting the nutrients it needs. If this continues, the grass could die from not having enough water and nutrients. Some folks living near the ocean might only have saltwater on their lawns.

Related Article: Can You Use Bath Bombs In A Hot Tub? Explained

How Can You Use Your Hot Tub Water?

Using Hot Tub Water

Dumping the water from your hot tub might seem wasteful, but there are a few ways to put it to good use. There is too much water in the hot tub to just let it go down the drain. In this section, we will go through a couple of examples of how you can do it:

Car Wash

The water you let out from your hot tub is enough to wash your car and maybe even a few cars from next door. When you start draining your tub, aim the hose towards your driveway. This way, you can use it to rinse your car as you wash it. Plus, positioning it right ensures the water flows safely towards the street without making your grass soggy.

Water Trees and Plants

If there’s no chlorine in your hot tub water, it’s great for giving your trees and plants a drink. If you think about watering your lawn with it, first check its pH since grass can be a bit picky. A pH between 7.0 and 7.8 should be okay, but you might want to try it on a small spot first. Remember to move the hose around every half hour so you don’t overdo it in one spot.


During a hot summer or if you live in a dry place, your home’s foundation or concrete driveway could benefit from some water. The amount of water in the hot tub is more than enough to pour concrete in front of your house. This helps to stop them from getting too dry and cracking

Related Article: How Many Gallons of Water in a Hot Tub?

If you want to learn more about hot tub water and its chemicals, watch this YouTube video:

Related Article: Can Hot Tub Be Cold? Explained

FAQ: People Also Ask

Is It Safe To Water Plants Using Hot Tub Water?

If your hot tub water is very salty or has bromine in it, you’ll want to be careful. A good tip is to let the water sit out for about a day or at least 7 to 8 hours. That’s because chlorine, often in hot tubs, evaporates quickly when left out in the open. Once you’re sure the chlorine levels are below 0.1 parts per million, go ahead and give your plants a drink!

How Often Does A Hot Water Tub Need To Be Drained?

Changing the water in a hot tub approximately 4 to 5 times per year is recommended. During drainage, it’s important to ensure that the water does not reach the grass surface to prevent damage.

Can I use my hot tub as a pool?

Indeed, it’s possible to transform your hot tub into a cold plunge pool. This can be done by directly integrating the chilled water supply and return water conduits from the chiller into your spa system. It’s essential to note that your existing spa pump will facilitate the water circulation through the chiller, as the chiller necessitates flow to operate effectively.

Final Thoughts

To sum up, we can see that using the water from a hot tub on your grass can be harmful. As long as the water doesn’t have a lot of salt, chlorine, or bromine, it won’t hurt your grass. Spilling some accidentally won’t be a problem, especially if you rinse the area with clean water afterward. When you’re emptying your hot tub using a hose, make sure to aim it at your driveway, not your yard.

Leaving chlorinated water from the tub out in the open can help reduce its chlorine level. But remember, pouring a ton of hot tub water straight onto your grass is not a good idea, as it might harm it. Instead, consider using that water to clean your car, driveway, or other items around your home.

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