What Water Should You Use in a Tower Garden?
Learn how to choose the best water source, manage water quality and pH, and keep your Tower Garden reservoir healthy.
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What water should you put in a Tower Garden? For many growers, the water coming from the tap or well can work—but what's already dissolved in that water matters.
A Tower Garden is a recirculating aeroponic system, so the same water remains in the reservoir while plants use it and you add more. Chlorine, chloramine, salts, minerals and other substances in your source water can therefore affect your growing conditions.
Let's compare city water, well water, reverse osmosis water, rainwater and other common water sources so you can choose the best option for your Tower Garden.
What's the Best Water for a Tower Garden?
Filtered water is our preferred choice when your source water contains chlorine, chloramine or other water-quality issues. Reverse osmosis (RO) water can also be an excellent option, especially when source water has high levels of dissolved salts or minerals.
Well water can work very well, too, but well-water quality varies dramatically by location. If you have hard water, high iron, high salinity or other known water-quality issues, testing the water can help determine whether filtration or RO treatment would be beneficial.
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Choose your water source and learn what to watch for.
Can You Use City or Tap Water in a Tower Garden?
Yes, but we recommend finding out whether your municipal water contains chlorine or chloramine.
Both are disinfectants used by water utilities, but they behave differently.
Chlorine
Free chlorine is less persistent in water and can dissipate over time. This is why letting chlorinated water stand has traditionally been used as a way of reducing chlorine before using the water with plants.
Chloramine
Chloramine is different. It is designed to provide longer-lasting disinfection as drinking water moves through the distribution system. Unlike free chlorine, chloramine does not readily disappear just because water has been left sitting out.
If your utility uses chloramine, simply filling buckets and leaving them outside isn't a reliable way to remove it.
💡 Not sure what your city uses?
Check your local water utility's annual water-quality report or contact
the utility and ask whether it disinfects with chlorine or chloramine.
Filtering City Water
A suitable water filter can help reduce chlorine and chloramine before the water goes into your Tower Garden. We use and recommend the GrowRite Garden Hose Filter as an easy option that connects directly to a garden hose.
Check the manufacturer's specifications rather than assuming every carbon filter removes chloramine.
Can You Use Well Water in a Tower Garden?
Yes. Many growers successfully use well water, but well water isn't automatically better—or worse—than municipal water.
The important question is what's actually in your well water.
Depending on your location, groundwater may contain varying levels of:
- Calcium and magnesium
- Iron and manganese
- Sodium and chloride
- Carbonates and bicarbonates
- Other dissolved salts
- Sediment
Some of these are normal components of water, but high concentrations can affect pH, nutrient balance or salt levels in a recirculating growing system.
When Should You Test Well Water?
Consider having your source water tested if:
- You already know your water is very hard
- You have significant iron staining
- Your water tastes noticeably salty
- You have recurring difficulty controlling reservoir pH
- Plants repeatedly struggle despite correct light and nutrient use
- You simply don't know the quality of the well water
For hydroponic growing, useful measurements can include pH, electrical conductivity (EC), alkalinity, sodium, chloride, calcium, magnesium and iron.
Is Hard Water Bad for a Tower Garden?
Not necessarily.
Hard water generally contains higher levels of dissolved calcium and magnesium. Those minerals aren't inherently harmful to plants—in fact, plants require both calcium and magnesium.
The bigger concern is the overall chemistry of the source water.
High alkalinity can make reservoir pH more difficult to manage, while high levels of dissolved salts such as sodium and chloride can create additional problems in a recirculating hydroponic system.
Hardness and alkalinity aren't the same thing.
Hardness primarily reflects minerals such as calcium and magnesium,
while alkalinity describes the water's ability to resist changes in
pH. A water test can tell you much more than simply knowing that your
water is "hard."
Can You Use Reverse Osmosis Water in a Tower Garden?
Yes. Reverse osmosis (RO) water can be an excellent source water for a Tower Garden.
Reverse osmosis removes a large proportion of dissolved salts and minerals from the source water. This gives you relatively clean water before you add your Tower Garden nutrients.
This can be particularly useful when your original water has high salinity, high alkalinity or other dissolved substances that make reservoir management difficult.
Do You Need to Add Minerals Back to RO Water?
You don't need to remineralize RO water simply because you're using it for your Tower Garden.
Tower Garden Mineral Blend A & B supplies the plant nutrients used in the growing system. Add the appropriate amount of Mineral Blend to the RO water just as you would when preparing your normal Tower Garden nutrient solution.
After adding nutrients, check and adjust the reservoir pH as needed.
Can You Use Rainwater in a Tower Garden?
Rainwater can be used, but the quality of collected rainwater depends heavily on how it is collected and stored.
Water collected from a roof can pick up:
- Dust and debris
- Bird and animal waste
- Roofing residue
- Airborne contaminants
- Material from gutters and storage containers
If you're collecting rainwater for an edible garden, use a clean, well-maintained collection system and consider filtration or testing when the quality is uncertain.
Also keep storage containers covered to reduce debris, mosquitoes and algae growth.
What Water Sources Should You Avoid?
Reclaimed Water
We don't recommend using reclaimed water in a Tower Garden unless the water is specifically approved for the intended edible-crop use and you understand its treatment and water-quality specifications.
Reclaimed-water standards and permitted uses vary by location, so don't assume that water considered suitable for irrigating a lawn is appropriate for a recirculating system growing food.
Lake, Canal or Pond Water
We also don't recommend filling a Tower Garden directly with untreated lake, canal or pond water.
Surface water quality can vary considerably and may contain sediment, microorganisms, salts, agricultural runoff or other contaminants that you can't identify simply by looking at the water.
Water From a Water Softener
If your home's water passes through a salt-based water softener, we recommend using a water source that bypasses the softener for your Tower Garden.
Salt-based softeners typically exchange calcium and magnesium for sodium or potassium. Adding unnecessary sodium to a recirculating growing system is something we want to avoid.
Tower Garden Water FAQs
Can I fill my Tower Garden with tap water?
You can use tap water, but check whether your municipal supply uses chlorine or chloramine. We prefer filtering city water when disinfectants or other source-water issues are a concern.
Can I let tap water sit overnight to remove chlorine?
Free chlorine can dissipate over time, but chloramine is much more persistent. If your utility uses chloramine, simply leaving water sitting overnight isn't a reliable removal method.
Is filtered water better for a Tower Garden?
It can be. Filtration is particularly useful when the source water contains chlorine, chloramine, sediment or other substances you're trying to reduce. The right filter depends on what's actually in your water.
Is RO water good for hydroponics and Tower Gardens?
Yes. Reverse osmosis water provides a low-mineral starting point before you add the Tower Garden nutrient solution and can be particularly useful when the original source water has high dissolved salts or alkalinity.
Do I need to add nutrients if I'm using well water?
Yes. Naturally occurring minerals in well water don't replace the balanced plant nutrition supplied by Tower Garden Mineral Blend A & B.
Continue Learning About Tower Garden Water
💧 Complete Water Guide
Learn about water quality, reservoir management, pH and other Tower Garden water basics.
Tower Garden Water Guide →🧪 Tower Garden pH
Learn why reservoir pH matters, the correct range and what can cause pH to change.
Tower Garden pH Guide →🌿 Tower Garden Nutrients
Learn how Mineral Blend A & B works and what nutrients it provides to your plants.
Tower Garden Nutrients Explained →🥄 How Much Nutrient?
See exactly how much Mineral Blend to add when filling or topping off your reservoir.
Nutrient Dosing Guide →Need a Garden Hose Water Filter?
Filtering your source water can be an easy way to improve the water you're putting into your Tower Garden.
Shop the GrowRite Garden Hose Filter
