What to expect when it comes to watering your arena

"How much do I need to water my arena?" or "How much water does TruTex Footing require?" are two questions we get asked on a regular basis.

There truly is no “one size fits all” answer to this question as there are many variables that influence the amount you need to water your arena but in this post, I’ll give you a few example scenarios and also a handy arena watering calculator to give you an idea of how many gallons of water you need for your arena to perform optimally.

Firstly, let’s highlight the primary factors that will influence your arena’s moisture requirements:

  • Whether the arena is indoor or outdoor
  • The average temperature in your climate
  • If the arena is in full sun or shaded
  • The amount of wind the arena is subject to
  • The overall depth of your footing
  • The size of the sand particles & additive materials

I think it’s pretty self-explanatory that an outdoor arena in full California sun in August is going to dry out at a much faster rate than an indoor arena in New York in the spring.

Heat and wind will of course increase the rate of evaporation and dry out an arena more quickly.

The less obvious factors may be the sand depth and particle sizes. The deeper and finer the sand, the longer it takes to dry out. The reason for this is that in order for water to evaporate, there has to be air present that isn’t already saturated to its dew point. 

In simple terms, deeper and finer sand has less dry air available between the grains to dry it out and by the same theory, coarser or rounder sands will dry out more quickly than finer sands as there is more void space between the particles.

So how much water does your arena actually need?

Making a very basic calculation of how much water you’ll need to apply to an arena requires understanding 2 things.

  1. The volume of sand in your arena (Length x Width x Depth)
  2. The ideal moisture % level you are trying to achieve.

The chart below shows the recommended moisture levels for TruTex products but you can adjust the desired percentage to calculate for other products as well.

ProductTruTex ElementTruTex EclipseTruTex Oasis
Moisture %8%10%15%

To make it easy to figure out how much water your arena would take to bring it from completely dry to the correct amount of moisture, we have included this handy arena watering calculator to do the math for you. 

Remember that when you use the full recommended product percentages in your calculation, this is assuming that the arena was bone dry throughout before watering.

Arena Watering Calculator

Ensure measurements are entered in feet.
Ensure measurements are entered in feet.
Insert your total footing depth, not including any compacted base layers.
Adjust this number according to the moisture % you would like to calculate.

Total: gallons

Ok, so that’s given us a calculation for the “worst-case-scenario” of how much water you would need to take your arena from being completely dry to being at the correct moisture level.

However, the best way to maintain a consistent footing is to keep the footing moist vs letting it become completely dry before watering it again and allowing the footing properties to go up and down like a rollercoaster, which will continually change the feel of the footing. 

This is where those variables we touched on earlier come into play…

How often do you need to water your arena?

The key here is to find a balance between the performance requirements of the arena, the volume of water you are able to practically apply in one session, the frequency that you will be watering and the rate the water will be evaporating.

It is common sense to assume that the longer you go between watering, i.e. the drier the arena, the greater the volume of water needed to bring it back to the ideal moisture levels. If you water the arena every day and it’s still pretty moist the next day, then you would need to put down a lesser amount of water than if you’re watering every four days. 

As the footing gets drier, the amount of support that the footing offers is also reduced so the more demanding the work being done in the arena, the more important the consistency of the moisture levels are.

In order to figure out how much water you would need to put down depending on the watering frequency, you will need to have an idea of the rate at which the water will evaporate in your specific arena conditions.

Below are some example scenarios

An indoor arena in an average temperature of 70-80 degrees with a 2.5″ sand depth may loose around 1% moisture per day to evaporation.

Let’s take this example using a standard dressage arena. Here we would type into the calculator: Arena length 196, Arena width 66, Sand depth 2.5, Moisture % 1.

This gives a result of about 200 gallons. What this means is that, assuming you had already added the full amount of water to bring the arena up to the desired moisture level initially, you would then need to add around 200 gallons of water per day in order to maintain the recommended moisture level on a daily basis.

If you prefer to space your watering sessions further apart, as many of us do… you would then multiply the original percentage by the number of days when using the calculator. So… if we wanted to water very 3 days instead let’s say… the calculation would be; Arena length 196, Arena width 66, Sand depth 2.5, Moisture % 3.

This gives us a result just over 600 gallons. So, if I wanted to water that same indoor arena every 3 days rather than on a daily basis, I would then need to apply about 600 gallons of water to bring it back up to the ideal moisture levels again.

Do bear in mind that we are definitely oversimplifying this process as evaporation is never linear. With this post the aim to give you a general idea of expectations when it comes to watering and the factors that will influence the rate of evaporation.

In this example, let’s take a 100′ x 200′ outdoor arena in a hot 80 degrees + full sun climate, with a bit of wind thrown in. 

In this scenario, the arena could loose as much as 3% moisture per day to evaporation so in this climate would likely require daily irrigation during periods of no rainfall.

For this arena, we would enter into the calculator; Arena length 200, Arena width 100, Sand depth 2.5, Moisture % 3.

The result we get is just over 900 gallons. Therefore, to keep an arena of this size in this climate at the desired moisture %, you would need to apply around 900 gallons per day.

A facility of this size would benefit from having a decent water tank or high-powered sprinkler system to be able to maintain this arena efficiently.

In our final example, let’s take a 150′ x 75′ indoor arena in an average temperature of 45 degrees. This arena might only loose as little as 0.5% to evaporation per day.

Again, assuming we have already applied the initial 1700 gallons of water to bring the arena from being completely dry up to the desired moisture level, we can adjust the moisture % field value in multiples of 0.5% according to the number of days we would like to go between watering.

  • Daily watering would require only 87 gallons of water
  • Watering every 4 days would require 350 gallons per watering
  • Watering once per week would require just over 600 gallons per watering

Summary

There is no one size fits all method or requirements when it comes to watering and with a new arena, there can be a learning curve when it comes to getting into a routine that is practical for you and also maintains a consistent enough feel to your footing.

The calculator above makes it easy to estimate the amount of water you would need to apply to reach different moisture percentage levels in your footing.

TruTex fibers help by reducing the rate of evaporation, which means you can space your watering sessions a little further apart. We have a lot of clients who have been able to reduce the frequency of their watering by up to 50% compared with how often they needed to water prior to adding the materials.

Boots on the ground Equestrian Knowledge

Working with a footing expert who understands the way that different types of sands and materials will interact with each other and your horse is crucial so that you can optimize the footing to your needs. Not only do the materials have to be carefully selected, but they also must be consistently maintained. 

TruTex is owned and operated by equestrians who, in the past had struggled to find the best footing additives for their arenas. That’s why they sourced the best ingredients and formed TruTex! Contact us at 812-558-2669 or through our online form if you’re still unsure about what product is perfect for you. You can also request a free personalized quote. We look forward to helping you and your equine business prosper.

The TruTex Team are all equestrians themselves and consists of riders, trainers and engineers who understand the science behind arena footing and equine biomechanics. They continually strive to expand their knowledge in all things footing and equine in order to produce the best products and service.
The TruTex Team are all equestrians themselves and consists of riders, trainers and engineers who understand the science behind arena footing and equine biomechanics. They continually strive to expand their knowledge in all things footing and equine in order to produce the best products and service.