How To Calculate Septic Tank Size Needed

Knowing how to calculate what size of septic tank you need is crucial. This enables you to make the right pick, thus saving you from future regrets.

We’re here to help you make such decisions by showing you what to look out for.

When it comes to installing a septic tank, size plays a crucial role. Septic tanks come in various sizes for a reason. These are meant to meet the varying needs of homeowners.

Certain households are small. For such, medium-sized or smaller tanks will serve. The same cannot be said for larger households. So, it all boils down to making a choice.

How Big Is The Septic Tank You’ll Need?

When dealing with septic tank size calculations, one thing always comes up, and that is water consumption. All the septic waste being generated by a household is directly tied to water use habits.

Daily actions such as laundry, tooth brushing, toilet use, showers, dishwashing, etc all involve the use of water.

These actions contribute a significant amount of water to your septic tank. As such, there needs to be an assessment of water use relative to the number of household members or occupants.

Having this knowledge helps with the choice of the most appropriate septic tank size.

Every building is designed with a fixed capacity. In other words, a building is expected to take or accommodate a certain number of individuals. The water use habits of the average persons are also taken into consideration.

Not everyone uses to water the same way. Some people use a lot of water while others don’t. Persons adopting water conservation practices also use less water than those who don’t. Certain climatic conditions also support more use of water than others.

With these points, it’s clear that water plays a key role in determining the most appropriate septic tank size to install in a home or building.

Standard Septic Tank Sizes For 1, 2, or 3-Bedroom Houses

There’s a strong correlation between the number of bedrooms and the size of a septic tank required. Many bedrooms simply translate to the number of occupants.

Based on the number of bedrooms, how big should a septic tank be?

A single bedroom apartment will require a septic tank measuring 1.9 cubic meters.

A septic tank measuring 2.85 cubic meters should serve for a 2 bedroom house. 3.8 cubic meter tanks will suffice for a 3 bedroom home.

How many bedrooms does a 1000 gallon septic tank support? If the property is less than 2500 sqm, this size should suffice for a 3-bedroom.

How To Determine The Size Of Septic Tank

When calculating the septic tank size required, it’s important to first breakdown all the key areas of water consumption. In other words, how you use water plays a key role in determining what tank size you need.

Important areas to highlight include toilet water use, bathroom water use, dishwashing, water taps use, lawn use, and laundry water use. These are all major water contributors that end up in a septic tank.

Factors To Consider In Septic Tank Sizing

Knowing how much water is used under each of these categories helps in arriving at an appropriate septic tank size.

For all of these key areas, the number of persons within the household is taken into consideration. The more people living within a home, the higher the water consumption rate is going to be.

  • Toilet Water Use

Quite a significant volume of wastewater generated comes from the toilet.

To create a better assessment of water use, you’ll need to consider the number of times each person flushes a toilet per day. On average, each person is expected to flush 4 times.

The volume of water the toilet uses is also important. Most standard toilets hold about 6 liters of water per flush. This is lesser (4.5 liters) for dual flush toilets.

  • Bathroom Water Use

People need to take baths and this contributes significantly to wastewater generation. To get an idea of water usage, you’ll need to find out the average number of showers taken by each member of the household.

For some, a single shower per day will suffice. Others have multiple showers. Find out the average number. Now, the average shower length also comes into focus. In most cases, the average shower length is about 10 minutes.

Other details like the total number of baths taken in a week as well as flow rates of showerheads are also important. All these give a picture of water consumption or use in the bathroom which is used in calculating septic tank size.

  • Dishwashing

Dishwashing also takes up or contributes a good amount of water that finds its way into the septic tank.

Details to be concerned about include the number of times dishes are washed by hand each day. The average time in minutes such water runs while dishes are washed is also important.

In the case of dishwashers, you’ll need to consider the number of times such dishwasher is used in a week. For a better context on water volume consumed, an average dishwasher uses about 25 liters of water per load.

Is yours different? If it is, you only need to include what applies to your situation.

  • Water Taps Use

Water taps are used for a variety of functions.

These include washing of hands, brushing teeth, shaving, washing of face, and so on. So, information is necessary on the number of times each member of the household uses the water tap.

For each time the water top is used, it could run anywhere from less than a minute to several minutes. So, include information on the number of minutes such taps run on average during each use.

  • Lawn Use

If you have a lawn, such a lawn needs to be watered each day. It will be necessary to include information on the number of times your lawns are watered in a week.

It is expected that a lawn will be watered each day. This adds up to 7 days a week.

The length of time such watering is carried out is also important to calculating water use. It will be necessary to also include information on the number of times your outdoor water taps are used.

  • Laundry Use

Laundry is among major water contributors to a septic tank. To calculate the septic tank size to install, you’ll need to understand your laundry water use habits.

In calculating, the number of loads by each member of a household per week is included.

On average, this should amount to about 7 laundry loads for each household member per week. The type of laundry machine also counts. Top loading laundry machines take up about 50 liters of water.

These are key components for calculating the size of the septic tank needed for a household or building.

Knowing these critical areas helps you avoid regrets that may follow after buying a septic tank that doesn’t fit your needs.

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