Pool Care Pool Water Chemistry

How to Refill a Swimming Pool Water After Draining

Draining and Refilling an Inground Swimming Pool

Pool refilling isn’t something most people are familiar with, especially if your swimming pool is less than two years old. However, from time to time, you might need to refill your swimming pool for various reasons that I will discuss in the next section.

When this time comes, how will you do it? This is the question that has brought you here. Right? I will go through everything you need to understand on how to refill your pool water. So, you better read it to the end.

Why is it Necessary to Refill Your Pool Water?

Apart from refilling the pool after draining to protect the walls and to get back to your swimming again, you still need to monitor the water level and maintain it. But why?

Compared to the water chemical balancing and maintaining pool pump and filters, monitoring the pool water level in either an inground or above ground pool seems super easy. Right? But this simplicity is the main reason it’s straightforward for many pool owners to overlook pool water refilling.

It’s crucial to keep the water level in both swimming pools at the midpoint of your pool skimmer. Pool slimmer is used to filter out those big debris as the water finds its way to the filter.

It offers a resting place for the dirt trapped in the skimmer basket, waiting for you to empty it preventing them from clogging the pipes and the filter.

Water enters it to the pipes and hose and flows the filter where it’s cleaned of the remaining debris and bacteria and return to the pool through the jets.

For the skimmer to be effective, your pool water level must be at the midpoint of your skimmer. If below it, the water won’t flow into the filter system, leading to other problems.

You could be facing severe skimmer damage. Since there is no water, the skimmer might draw air into the filtration system.

When this happens, your pool pump motor can burn out. And you know what, replacing the pool filtration system can be quite costly. That’s why it’s best to refill your pool water frequently.

What is the Best Water Source to Refill Water Pool?

There multiple ways out there that you can use to refill your pool water. What method you use depends on how much water you need and the size of your swimming pool.

But in general, all the techniques can work, but some will be faster than the other. What’s more, each of these methods has its pros and cons.

Let us go through them individually.

Option 1: City Water

Almost every home in the urban cities uses city water. If you have a tap in your backyard and pay water bills, you’re using city water.

City water is one of the many ways on how to fill a swimming pool fast. You can use it in filling a new swimming pool with water or refilling your old swimming pool.

All you need is a garden hose. Hook up one of its ends to the outdoor tap and direct the other end inside your pool.

It might be one of the easiest ways to refill your pool water. However, it can be highly pricey depending on where you live, city rules and regulations, and the volume of water your pool need.

Limited water supplies, drought, or natural disaster, can mean you’ll need to pay a premium for filing your pool water. It could happen, especially where there is water rationing.

The overall cost to pay to the city water services will vary depending on the supplier’s local water rates.

And you know what, they might also charge you with an excess usage fee, especially during unusual conditions like a draught. If you’re on municipal sewage, you might even get a receipt of the sewage fee.

Most people do escape the extra sewage fee to call the local utility and let them know they are filling their swimming pools.

You could try it. They might go easy on you and give you a discount or even cancel the whole sewage fee altogether.

Remember, the speed of filling your pool water will depend on the water pressure and the garden hose diameter – the bigger, the better.

Plan your time well, as you might need at least a day or two to fill your average-sized swimming pool.

Consult your nearest local utility office to get the total amount you need to refill your pool water with city water.

Option 2: Well Water

Well water is a common source for refilling pool water among most pool owners. It’s a natural source that might be in your back, ready to supply water capable of filling your pool. It can save you money by filling your swimming pool.

All you need is a well water pump that can get dip enough to give you sufficient water supply to refill your pool water.

Your well pump should be capable of pulling the water out of the well and also pump it to your pool. Check how deep the well is and the distance from it to your swimming pool.

With well water being free, it does have a few characteristics that you will need to keep an eye on when using it.

The Mineral Problem

With well water coming from the underground, it passes through many minerals with some like hydrogen sulfide get dissolved in it.

Those elements permeating the water table get filtered out by the city water plants. But since you’re pulling the water directly from the well, you will be getting everything the water carried with it.

That can be an issue for you as all the excess minerals can affect your pool sanitizer and balancing, giving you a water chemistry headache.

What more, Sulphur compounds can prevent the pool shock from being effective. Other metals like iron and copper can damage pool hardware, while calcium and others can stain your pool walls or liner.

If you use the well as the only water source for your home, you might have a connected softener system and a pump too.

If that is the case, you don’t have to be concerned with the contaminants. You can connect a garden hose to the tap and use it like you’re getting from the city water.

However, remember you’ll be using the softener systems to clean thousands of gallons of water. It’d be best to factor in the salt and electricity you’ll need to pump water into your pool. But there is option of getting a solar well pump, which can save you electric bills.

If you are getting the water directly from the well without a softener, test it for the minerals and metals before starting the pump. Use a hose filter to clean all the metals out if their levels aren’t alarming.

Can the refilling run a Well Dry?

The water from a well might be free, but the capacity can be an issue. It’d be best to make sure it can deliver the amount of water you need to refill your swimming pool.

Refilling your pool by running your well dry can force you to drill a new one, and that can cost you a lot, even thousands of dollars, and waste your time.

If you think your well doesn’t have enough water to refill your pool and leave you with enough water for residential use, don’t risk it.

That is something to think of when refilling your swimming pool after draining it during repair or cleaning.

You can use an online pool calculator to know the exact volume of water you need to fill your pool.

Option 3: Pool Water Delivery Service

Pool water delivery service works just like food delivery service. All you need is to make a call for pool water delivery near me or make your order online, and the water will arrive at your doorstep soon.

The best part is, you don’t have to be home when the delivery guys deliver the water. They can roll up the transport truck, drop in the drain hose and your swimming pool in no time.

When you get back home, you’ll find your pool water-filled and waiting for you to test and balance, sanitize, and you can start swimming.

Some pool water delivery companies even make things simpler for pool owners by delivering chlorinated water.

However, it’d be best to test the water and balance before you can start swimming; it’s crucially necessary when refilling the pool after draining.

The huge disadvantage here is the high pool water delivery cost you’ll pay. However, if you don’t have a well and your city water is under rationing, it might be your best option.

Don’t be afraid to shop around. Get quotes from several local suppliers, compare that to your costs for a city water fill-up, and don’t forget to factor in the time you’ll save compared to the trickle of a garden hose or your average pool pump. The bottom line might be sunnier than you’d expect.

Always try to find the best pool water delivery. Shop around and try to get delivery quotes from pool delivery companies around you. Remember to consider the amount of pool water you need no to pay for the whole swimming pool, and you just needed a few gallons for refilling.

How Do You Know the Amount of Water Your Pool Needs?

Are you refiling a new or old swimming pool? If you’re swimming pool has already been in action, the chances are you already know its volume.

But if you’re filling a newly built pool, refilling yours for the first time after draining it, or after buying a new house, you might want to do some calculations to know the number of gallons it holds.

You might also be needing a small amount of water to refill the water lost by evaporation or splash.

The calculation will help you not overspend on the amount that you don’t need. It can also help you budget for any upcoming refills.

You can do the calculations automatically using the available online calculator. But if you want to understand how all the math is done, you will need to take some measurements and then perform the calculations according to the following easy formulas.

Square or Rectangular Pools with Constant Depth

Length x width x depth x 7.5 = volume (in gallons), with 7.5 being the number of gallons in each cubic foot.

Square and Rectangular Pools with Variable Depth

Length x width x average depth x 7.5 = volume (in gallons)
(Deep end depth + shallow end depth)/2 = average depth

Circular Pools

π (3.14) x radius squared(r2) x average depth x 7.5 = volume (in gallons)
In short form: π x r2 x average depth x 7.5 = volume (in gallons)
(Deep end depth + shallow end depth)/2 = average depth
Radius = the distance across the pool top/2
π = pi, a mathematical constant.

Kidney or Irregular Shaped Pools

You can use Length × Width (average) × Depth (average) × 7.5 for smaller pieces and then add them up.
Or 0.45 x (A+B) x length x average depth x 7.5 = volume (in gallons)

How Frequent Should You Drain Your Pool?

How frequently you need to drain your pool depends on the current situation in your pool. You need to understand your pool maintenance routine to know when to change the water.

When your pool water is out of balance, it can be quite expensive to get back on track. That’s why pool experts recommend changing the pool water periodically.

You should do pool water draining and refilling after every 3-5 years. By this time, your water will be saturated with various chemicals, minerals, and more.

Draining the water gives you time to acid wash it or give it a deep clean. It’s also easier to balance and maintain pool water chemistry when the water is fresh.

Your swimming pool might also need some repairs, especially on the floor tiles. Considering you can handle the repairs while all the water is in there, you will need to drain it and refill it once you’re with the repairs.

Why do pools lose water?

Other than draining your pool water, your swimming pool might still lose water and require refilling. But how? Here are the four ways your swimming pool could be losing water.


After reopening, you’ve to take the pool cover off and expose the water to the hot sun rays. As the heat warms the water, the surface water evaporates. As time passes by, most weeks, your pool water level can drop.

Of course, you can prevent this by installing a pool solar cover or rings that protect the water from evaporating while also lowering your heating bills. They absorb the sunray and trap them inside the pool to heat the water. The covering allows the moisture to get trapped in the pool too.

Active swimming

If you hold multiple pool parties with active swimmers that splashes water everywhere, you can be sure you will be adding water very soon.

When the pool water gets splashed out, it doesn’t return to the swimming pool as it might contain contaminants. So, when the swimmers splash it, the water has no replacement. With time, the water level starts to drop.

The best solution for this is to limit the number of pool parties you hold or get a warning to the active swimmers to limit the splashing. Be prepared; this might make you unpopular.


When vacuuming your pool, some water will get sucked out with the dirt and the debris. And since you’re taking out the debris and contaminants, there is no way you can let them back into the water.

That means every time you vacuum, your swimming pool loses some water. When you repeat this for a couple of weeks or months, the water level drops, forcing you to refill it.

The best solution is to use an automatic pool vacuum with dirt filters to clean the water and return it to your pool.


Backwashing requires you to reverse the water flow and drain it out of the swimming pool through the filter backwash drain. When you get overenthusiastic with the process, you can lose a lot of water.

With pool filter backwashing being a necessary maintenance practice, you can take advantage of the sight glass to monitor the water. Once the water becomes clear while you backwash, stop the backwashing.

You can also keep your pool chemistry balanced as it will help take some cleaning tasks away from the filter. As you well know, the more strainers the filter is, the more backwashing you will have to do.


If your swimming pool water level is dropping even when the weather isn’t that hot, you’re doing less backwashing, and it has low usage, you have to check for leaks on the liner or the filter piping.

And with evaporation and splashing being normal, it’s can be tough to tell if your swimming pool is leaking.

If you find a leak, take the necessary steps to fix it. If it’s beyond your DIY skills, get a professional right away.


Refilling your pool water is an easy task, especially when you have a reliable source of water. The best method to fill your pool among the three will depend on the situation at hand and the service’s availability.

A well beat is the best and free, but it needs a softener system and electricity to run the well pump. City water and pool water delivery costs might be similar depending on the state and its water usage laws. Pick the best method according to your convenience.

About the author

Sharif Miah

Hi! I'm Sharif, the founder of Globo Pool® and I have been working in the pool & hot tub industry for the last few years. I love to share my experiences with people & hope you are enjoying my information and lessons!

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