Guide to Watering Your Worm Compost Bin: When, How Often, and How Much (2024)

Similar to over-feeding, there is tendency to over-water worm farms when getting started. This can lead to conditions that harm your red wigglers or possibly cause them to perish. 

With the above in mind, let's take a look at how much and how often to water your worm farm and the golden rule of how wet your worm bin should be.

Do Worms Need Water?

Yes - worms need water to survive. Water makes up around 70% of an earthworm's body weight. Worms also absorb oxygen through their skin so worms require water to breathe. Without a moist environment worms will dry out very fast and perish. A lack of water will also slow down worm breeding and eating, so ensuring a moist environment is critical to their survival.

Worms are moist and need water water to survive!

How Much Water Do Worms Need?

Worms like red wigglers need a damp, but not wet, environment to thrive.  The ideal amount of water in a worm bin is just enough to produce 1-2 drops of water when you squeeze a handful of bedding. The best way to get this consistency is to use a sprayer or spray nozzle to water the worms.

Think about your yard or a local park, if you dig down a few inches the ground is usually moist but not dripping wet. That's the level of moistness to go after in your worm bin!

**If you are new to worm composting or looking for general guidelines on setting up, feeding, and caring for your worm bin, check out our Complete Guide to Starting a Worm Bin ***

Looking to buy compost worms, we offer red wiggler compost worms in 100-2000 count as well as worm composting bins for indoor or outdoor worm composting.

Wondering how many worms to buy for your bin? Our friends at Montana Farm Life but together this handy vermicompost bin calculator.

How Often Do You Water a Worm Farm?

How often to water a worm farm depends on several factors, including temperature, sun and wind exposure, and humidity in your area. Indoor worm bins should be watered 1-2 times per week, while outdoor worm bins exposed to sun or wind will need to be watered more often (every 1-3 days). The key is to make sure the bed always stays moist like a wrung out sponge.

How to Water Your Worm Bin

To water your worm bin use a spray bottle or nozzle to get an even distribution of water on the bedding. You ultimately want 1-2 inches of water to come out when you squeeze a handful of bedding. You only need to water the top few inches of your worm farm, so water the top layer and then use your hand to turn over a few inches of bedding and water the top layer again. 

We like simple rules at Brothers Worm Farm, so here are a few to go by when watering your worm compost bin:

• Rule #1: Moderation! You can always add more water. 

• Rule #2: Never pour water into a bin. This will lead to over-watering or inconsistent moisture throughout the bin.

Tip #1: We've found a spray bottle or light mister works best to ensure the correct amount of moisture and an even distribution throughout the worm farm.

• Rule #3: Target watering your worm farm 1-2 times per week (if it's indoors), around the same number of times you should feed worms. Watering daily or multiple times per week is not normally required. In many cases you can water every week or so - it depends on temperature, humidity, and other factors so monitor the worm bin and if you see it getting dry give it a good misting or spray. Outdoor worm compost bins usually require more frequent watering, so check it often and keep the top later moist!

• Rule #4: Don't let water accumulate in the bottom of your worm farm. If water accumulates, gently dump it out or mop it up with paper towels. This is a sign you are watering too much so adjust your watering schedule and amounts!

• Put another way, water (or "tea" or "leachate" as some folks incorrectly call it) should not be collecting in the bottom of your bin. The "tea" is full of harmful bacteria and should be thrown out and not used on your plants or garden.

• Rule #5: Make sure the top inch or so of your bin is the most moist part of the bin. The bedding should get more dry as it goes to the bottom of the bin. Worms are attracted to water and will migrate to it in a worm farm. If water collects on the bottom many of the worms will find that attractive and migrate there, which is problematic since their food is placed in the top 1 inch of the bin.

Keep in mind that most of the food (e.g., fruits and vegetables) you feed compost worms will likely have high water content. This will help keep the feeding areas moist and those areas may not need as much water over time as other areas (e.g., the outer edges of the bin tend to get the driest over time).

When watering I will often water the outer edges of my home bin more than the middle areas that remain moist from the high water content in my worm's food.

In summary, remember to moderate and not over-water your bin, keep the bottom areas drier than the top areas of the bin, and don't let water accumulate in the bottom of the bin. Your worms will thank you!

Frequently Asked Questions - Watering a Worm Farm

How Wet Should Worm Bin Be?

Worm bins should be moist but not too wet. A good rule of thumb is to moisten the bedding so that when a handful of bedding is squeezed in your hand, 1-2 drops of water come out. It's also important to note that water should not be collecting in the bottom of the worm bin.

Can You Over Water Worms?

Yes, you can over water worms in a worm bin, which can lead to several issues in your bin. Over watering worms can lead to water collecting in the bottom of the bin, which can attract worms and move them away from the food at the top of the bin. Over watering can also lead to mold and odor issues in your worm farm.

How Do I Know If My Worm Farm is Too Wet?

If water is collecting in the bottom of your bin then your worm farm is too wet. In addition, if you squeeze a handful of bedding from the worm farm and more than a few drops of water emerge, then your worm farm is also too wet. The ideal amount of water in a worm farm is for 1-2 drops to come out when a handful of bedding is squeezed.

How Often Should you Flush a Worm Farm?

You should not flush a worm farm. Flushing is unnecessary and will result in too much water being added to the worm farm.  If too much water is added to a worm farm, it will collect at the bottom of the bin and attract worms, or lead to other odor-related issues. Worm farm bedding should be no wetter than a wrung-out sponge.

Can I Use Tap Water In a Worm Farm?

Yes - it is perfectly fine to use tap water in a worm farm. Tap water is used in worm farms throughout the US and around the world. Although some have concerns about chlorine or other chemicals in tap water, these chemicals are in trace amounts and will not impact the worms in your worm farm.

Can you Overfeed Worm Farm?

Yes, it is possible to overfeed a worm farm, which can lead to several serious consequences for the worms. Overfeeding a worm farm can result in mold and be an attractant for insects, and in the worst case excess food can ferment and cause protein poisoning and death in worms. As a general rule, feed worms 50% of their weight and they should finish each feeding in 2-3 days.

Have any other questions we haven’t answered? Check out our other related posts:

1 - What are the Best Worms for Composting?

2 - Worm Composting 101 - The Complete Guide to Worm Composting 

3 - Guide to the 6 Most Common Worm Bin Problems (and How to Solve Them!)

4- How Do Earthworms Reproduce - Guide to the Prolific Red Wiggler Breeding Process

Or just shoot us an email or check the other tips and how to articles on our blog. Thanks for reading and happy farming!