Guide to Watering your Worm Compost Bin: When, How Often, and How Much (2023)

Water makes up around 70% of an earthworm's body weight, so having moist conditions in a worm bin is a critical element to their survival.

That said, the rule of moderation applies to watering your bin.

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

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. 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 to Water Your Worm Bin

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 1-2 times per week. 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 bin and if you see it getting dry give it a good misting or spray.

• 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" 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!

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!