Guide to Draining Koi Ponds, Goldfish Ponds, and Water Gardens (2021 Updated)
Draining your garden pond may sound like a huge hassle, but it’s actually a very simple task that can be carried out in a variety of ways. Depending on the size of your pond, and just how much water you’re looking to drain, most ponds can be emptied in under an hour if using the right equipment and technique. Whatever your pond size, this guide explains the easiest ways to drain your water with the least amount of trouble so you can get on with your day!
Before you start – Do you actually NEED to drain your pond?
Even though draining a pond is a fairly simple task, you should ask yourself if you actually need to drain your water to get the job done. If a pond is mature it will have a very complex ecosystem, packed with beneficial bacteria, micro-organisms, and all sorts of insects and plants. Draining the water will have a negative effect on this ecosystem, and it will take a long time for the pond to become established again after re-filling with mains water. If your pond has fish, this is even more important as goldfish and koi both require a healthy population of bacteria in ponds to stay safe from harmful substances, such as ammonia and nitrites.
If you need to fully drain a pond to repair or replace pond liner, then total drainage may be the only option. Likewise, if you’re upgrading your water garden or redesigning the pond, you’ll probably need to start from scratch. However, if you’re simply looking to clean the pond you don’t actually need to drain it fully if you invest in the right equipment (i.e., pond vacuum). Draining pond water should always be a last resort, as it will place great stress on the natural ecosystem, which includes damage to the nitrogen cycle and beneficial bacteria populations.
Why drain a pond? Reasons draining may be required:
- Repairing/replacing pond liner
- Redesigning the water garden
- Moving fish between different ponds
- Performing heavy water changes
- Catching fish to check for parasites/injury
Where to Drain Pond Water? What’s the Best Option?
If you’re in the process of draining pond water, don’t just let it go to waste by emptying straight into a sewer drain! Pond water is packed full of nutrients and micro-organisms, making it a fantastic natural plant fertiliser. In-fact, pond water can have such a good amount of nitrates and phosphates, it can be better than some commercial fertilizers.
To make the most of your pond water when draining, we recommend emptying the water all across your garden where plants and trees are the densest. If you have vegetable gardens, add some water there! If you have fruit trees, give them some love! It’s great for basically everything, and even emptying the water straight into the middle of the lawn is better than in a sewage drain. The nutrients will slowly spread throughout the soil and be taken up by the deep roots of nearby trees and shrubs.
If you have a small garden, you could also simply top up a few buckets or water cans with pond water and then empty the rest in the drain. The water will remain an effective fertilizer for plants for a few days, so you can use it to water through the week for watering purposes.
Tips for Improving Water Quality when Refilling Ponds
A final thing to note is if you intend to refill your pond with mains water after draining, the water should be treated accordingly to improve it’s quality and reduce any negative impact on the ecosystem. This applies to both partial drainage and full water drainage, and this process should be always carried out on ponds with any kind of fish, such as koi and goldfish.
Water added directly from the mains supply will have high amounts of chlorine and chloramine, which can cause burns to fish and will quickly kill beneficial bacteria. Water should be safely dechlorinated before adding to a pond to ensure wildlife is safe and water quality is remains stable.
As well as this, after draining a pond you will have likely destroyed a portion of the natural bacteria population, so supplementing with a beneficial bacteria product can help kick-start your biological filtration again. To top things off, you should also perform a water quality test to ensure that water is safe for fish, which includes taking readings for ammonia, nitrites, pH, and KH. All these things can be impacted by water changes and drainage, so a test should be carried out before and after so you can compare values. For further reading on these topics, check our dedicated articles below:
- Guide to Dechlorinate Pond Water for Fish
- Beneficial Bacteria Supplements for Ponds
- Testing Water Quality & What to Look out For
How to Drain a Pond Quickly and Easily
Method 1) Using a Submersible Pond Pump
Recommended for: Small-Large Ponds (Fast Drainage)
Probably the easiest way to drain a pond is to use your pond pump, with submersible models being the preferred choice to due to easier drainage. To start emptying a pond using a submersible pump you just need to position the out-take hose into your garden or the area you want water drained. You would then need to place the submersible pump at the deepest point of the pond to ensure you can drain the maximum amount of water in one sitting. If your pond is particularity deep and you want to drain water to a distant location, you would need to make sure your pump has the required water lift height power for the task. Most pond pumps will have a maximum “head height” value in their manual, which indicates the maximum height they can lift pond water before losing power. The higher this value, the deeper you can place the pump and the further away you can drain your pond water.
You can also drain a pond using an external pond pump, although this could be a little trickier depending on the method of installation. If your external pump is below the water line with a fixed intake, you will have trouble draining much water below the intake height. To solve this, you can purchase a hose extension and fit this to the intake and place at the deepest water point. You would then position the out-take hose into your garden or over a drain to start emptying water, just like a submersible model.
A submersible pump is still an easier option here, and as it’s always good to have a backup pump, so you could invest in a cheap model with good water lift heights just for water drainage purposes. Depending on how often you need to drain water, this could be a good long-term investment for easier maintenance.
Method 2) Using a Solar Power Pond Pump
Recommended for: Small Ponds (Slow Drainage)
If you have a much smaller pond, such as a preformed pond, and also want to save money, you can consider using a solar pump to slowly drain your water. This is a good choice for small ponds in summer months, as the intense sunlight throughout the day can easily power the pump without much downtime. Most solar pump models are also designed for use as fountains, so they will have a respectable water lift height in comparison with their low flow ratings. Since this option is only really suitable for shallow ponds, you shouldn’t run into any problems pumping water to ground level and into your garden.
For maximum water drainage, you would want to look for a solar pump with a large capacity solar panel and preferably a flow rating of between 200-500 GPH. Head height is usually a few meters for solar models, but the stronger the GPH, the higher the maximum head height usually is for the pump. Since you don’t need an electric mains connection to power this type of pump, it works well to drain ponds in more remote locations or if a spare mains socket is not available on site. Most models will come with all necessary hose piping, but you may need to purchase some extensions if you want to drain further from the pond.
This method of draining a pond won’t be suitable for larger ponds, and is also much slower than using an electrical pump. With that said, it’s a good choice if you have a small pond or if you’re not in a hurry to remove water quickly. Solar pumps are also a great way to save money, and they double as nice water features for extra aeration!
Method 3) Using a Pond Vacuum Cleaner
Recommended for: Small-Large Ponds (Fast Drainage)
Although we wouldn’t recommend a pond vacuum JUST for draining a pond, they’re a flexible solution if you also want extra help with cleaning in the long run. All pond vacuums will be able to perform basic cleaning duties, but only premium models will be suitable for fast water drainage, as cheaper models won’t have an efficient discharge feature.
In terms of both cleaning and draining water, we recommend the Oase Pondovac 4, as it features an impressive automatic discharge system that allows it to stay constantly operational. Many vacuums with a discharge feature will need to temporarily switch off suction so they can start discharging water from a back flush port. This isn’t a problem if you’re in no rush cleaning, but if you want a vacuum for both cleaning and large-scale draining, it can hugely extend the drainage time.
Oase’s vacuum contains two high capacity storage chambers, and as when becomes full, the vacuum automatically switches to the empty container and continues suction. After the switch, the vacuum starts to discharge stored water from a outlet hose on the back, but never loses suction and continues to fill the empty chamber alongside. This process continues as one becomes full, and the other empty, meaning almost constant operation! The outlet hose is also fairly long and can be easily positioned in your garden, although you may need some extensions if you want to drain extra large distances.
We would still recommend a regular pump for most situations (as many pond owners will have this on hand), but if you also like the idea of easier pond cleaning, you really can’t go wrong with a quality pond vac.
Method 4) Using a Siphon Hose/Pump
Recommended for: Small Ponds (Very slow drainage)
If you have a small pond which is elevated and you can position a hose lower than of the deepest point of the pond, you can slowly siphon water using a hose pipe. This can be done with any kind of hose, although we would recommend investing in one with a manual pump feature so you don’t need to actually suck water through physically. A pump also means you don’t have to necessarily position the outlet hose lower than the pond, although this only works if you manually work the pump as it it drains.
Filters aren’t necessary as you’ll just be discharging into your garden or the sewer, but you’ll want to definitely have a hand pump and a good length of hose for easy extraction. Most siphon hoses, even with hand pumps, will only be able to move water at a rate of 2-10 gallons per minute. If you go with a larger hand pump (10 gallon flow rate), it would take you around 20 minutes to drain a pond containing 200 US gallons of water. If you don’t use the pump and just let the water drain, you’re looking at 10x that amount of time – so a couple of hours per 200 gallons.
If you don’t mind the wait, or want more control of how much you discharge in a small pond, using a siphon hose and hand pump is a certainly an option you can try.