Water Demand Calculator

Created by Agnieszka Syrek
Reviewed by Dominik Czernia, PhD and Adena Benn
Last updated: Jan 18, 2024

With our water demand calculator, you can quickly find the basic parameters for estimating the average water usage in a given area or population. By accurately determining this demand, policymakers and water management authorities can make informed decisions to effectively plan and manage water resources, ensuring the sustainable provision of water for domestic, commercial, and industrial needs.

It is essential to incorporate factors such as population size and water consumption per capita when using our water demand calculator. However, be advised we only provide you with an approximation of the real needs. Read on to find out more about the water demand definition and see how to calculate water demand. We also provide information about the average daily water demand per person in the USA.

If you're here for more personal information, we encourage you to visit our water intake calculator to find out how much water you should drink daily. Alternatively, you may visit our dog water intake calculator to do the same calculations for your dog.

What is water demand?

Water demand can be defined as the total water usage of an area per unit of time. Typically, we express it in terms of daily usage or average usage per second.

To find it, you can multiply the average daily water demand per person by the population size living in the area or city. We write more about it in the following sections.

Water demand formula

The water demand calculator is based on the following average daily water demand formula:

$\footnotesize \mathrm{ADD} = \mathrm{LPCD} \times P + 10\% \times P$

where:

• $\mathrm{ADD}$ — Average daily water demand;
• $\mathrm{LPCD}$ — Liter per capita per day; and
• $P$ — Size of the population.

You can find the above water demand formula, e.g., on the , which assumed $\mathrm{LPCD} = 225 \mathrm{\ L/(capita · \! day)}$ which we set as the default value in the water demand calculator. The equivalent in gallons is $60 \mathrm{\ gal/(capita · \! day)}$.

🔎 As you have seen above, we base our calculations on liters, but you can switch the units in the calculator panel or use our volume conversion if you prefer other units.

Maximum and peak water demand calculator

So, you know how to calculate water demand from the population. There are also two related concepts to the average daily water demand, namely:

1. Maximum daily water demand — the largest volume of water that may need to be delivered in a day:

$\mathrm{MDD} = 1.4 \times \mathrm{ADD}$

2. Peak hour water demand — the maximum volume of water that may need to be delivered in a second:

$\mathrm{PHD} = 2.3 \times \mathrm{ADD}$

3. In the water demand calculator, we estimate both of them. You can change the default ratios $1.4$ and $2.3$ in the advanced mode of our calculator to adjust the parameters to your needs.

Managing water demand: factors and strategies

Average daily water demand serves as a critical metric for effective water management. Policymakers can estimate the average daily water usage of a region by analyzing factors such as:

• Population size;
• Water usage patterns; and
• Economic activities.

This information guides decision-making processes to ensure adequate water supply, address potential shortages, and implement conservation initiatives.

In addition, managing maximum daily water demand is crucial to ensure a reliable water supply during periods of high consumption. Strategies such as water conservation campaigns, peak load management, and infrastructure upgrades can be implemented to effectively meet peak water demand while maintaining a sustainable water supply for all users.

By understanding the factors influencing average daily water demand and implementing appropriate strategies, we can achieve a balance between urban growth and conservation, to ensure the responsible and efficient use of water resources for present and future generations.

How does water demand impact the balance between urban growth and conservation?

Water demand is a vital consideration in urban planning, especially in rapidly growing areas. By integrating water demand calculations into urban development plans, policymakers can ensure that adequate infrastructure and resources are in place to meet the needs of expanding populations.

This approach promotes sustainable growth while prioritizing water conservation and efficient usage practices.

Reducing CO2 breathing emissions for sustainable water management

Surprisingly, reducing CO2 breathing emissions is also essential for sustainable water management and mitigating water demand. CO2 emissions contribute to climate change, impacting water availability and quality.

We can mitigate climate-related water challenges by reducing emissions through sustainable practices in energy, transportation, and industry. When we promote water-saving behaviors, invest in efficient technologies, and raise awareness of the link between emissions and water demand, we make a step toward a sustainable future.

To assess your individual CO2 breathing emissions and understand their impact on your body, use our CO2 breathing emission calculator.

FAQ

How do I calculate water demand?

To find water demand in a specific area or city:

1. Determine the size of the population in this area.
2. Multiply it by the average daily water usage per person.
3. Add 10% to the result to include any potential water waste.

You obtained the average water demand per day for the area.

What is the water demand for a city with 100,000 residents?

The estimated average water demand for the population of 100,000 is 6.6 million gallons per day.

The maximum water demand is assumed to be 1.4 times greater and equals 9.24 million gallons a day, while the peak hour water demand is approximately 175 gallons per second.

What is the average water usage per person?

One person's average daily water usage in the United States can be even more than 130 gallons (or 500 liters). We use it mostly for showering, bathing, flushing our toilets, washing laundry, and doing dishes. We use only a small part of it for eating and drinking — around 5%.

What is the average daily water demand in United States?

The average daily water demand in the United States was about 322 billion gallons per day in 2015. Its equivalent in liters is 1,220 billion liters per day.

California and Texas were the states with the highest water consumption, while Hawaii, Alaska, Oklahoma, North Dakota, and South Dakota had the lowest estimated water use.

Agnieszka Syrek
Population size
Water requirement per capita
US gal/day
Average water demand
US gal/day
Maximum water demand
US gal/day
Peak water demand
US gal/s
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