How Many Pumps Do You Need for a DIY Hot Tub?

Last updated: September 2026

If you’re building a DIY hot tub, working out how many pumps you need is one of the first plumbing decisions. Get it right and you get strong jets and a quiet, efficient system. Get it wrong and you end up with weak jets or a pump doing two jobs badly.

This article is for DIY builds. If you’re buying an off-the-shelf tub, the manufacturer has already made this decision for you.

Types of pump

There are two jobs to cover in a DIY hot tub:

1. Jet pump: a high-flow pump that feeds your jets.
2. Circulation pump: a small, efficient pump that runs the filter and heater, usually for hours each day.

Pumps come in single-speed and two-speed versions. A two-speed pump can do both jobs (low speed for circulation, high speed for jets), which is why it’s common in tubs with one pump. If you want to know more, my ultimate guide to hot tub pumps covers the basics, and can I use a variable speed pump in a hot tub covers the newer alternatives.

How many pumps for the jets?

DIY hot tubs tend to have fewer jets than factory plastic-shell tubs. As a rule of thumb, one large jet pump can run up to around 16 jets, depending on the distance and layout of your plumbing. The further the jets are from the pump, and the more bends and valves in between, the more friction you have and the less flow reaches the jets.

The maths is simple. Each jet needs about 10 GPM (gallons per minute), so 16 jets want around 160 GPM. But a pump’s rated flow is only a starting point. What you actually get depends on the pump curve and the resistance of your system, so always check the curve for your pump rather than trusting the headline number. My guide to sizing a hot tub pump shows how, and DIY hot tub jets explains how many jets you really need.

For a basic build with an electric heater, one two-speed pump can do everything. On low speed it handles filtration and heating and on high speed it powers the jets. This is simple, but it is less popular now that so many DIY builders add an air source heat pump, gas heater or solar.

Flow rate and plumbing friction

Alternative heating makes flow more important. Every bend, tee, gate valve and ball valve adds friction and cuts your flow. If the system can’t deliver enough GPM to the jets, you lose power.

The water takes the same route every time: pump, then filter, then heater, then jets. So your system is only as good as its weakest link. For example, a powerful pump feeding a restrictive sand filter might only manage 80 GPM. At about 10 GPM per jet, that’s enough for 8 jets, not 16. Read can I use a sand filter on my DIY hot tub before you choose one, and see DIY hot tub plumbing for pipe sizes.

The case for multiple pumps

To get round flow limits, most DIY builders split the duties:

• A dedicated jet pump for the jets.
• A smaller circulation pump for heating and filtration.

The jets get the full power of their pump. The small pump does the everyday circulation for much less electricity than a big pump on low speed. A circulation pump is also the right partner for an external heater such as an air source heat pump. See how to add a circulation pump to a hot tub and my guide to hot tub heaters.

Adding more jets

If you want more than about 16 jets, you’ll need another jet pump. With 32 jets, for example, you’d need two. Add a pump for every 15 to 16 jets to keep the flow and power up.

Water features

For waterfalls or water blades, I recommend a separate pump for each feature. You can size the pump for that feature, and you get independent control. That’s handy when the cover is on, because you can switch the waterfall off without affecting the jets or circulation. See adding a water feature to a DIY hot tub.

Quick summary

Job	Pump
Jets	1 jet pump per roughly 16 jets (about 10 GPM per jet, check the pump curve)
Filtration and heating	1 separate circulation pump
Each waterfall or water blade	1 pump per feature

More pumps cost more upfront, but you get far more control, and the jets and circulation don’t fight each other.

Want the plumbing worked out for you?

My hot tub plans include the full plumbing layout, with pump, filter and heater positions worked out. If you want a hand with your own layout, there’s also a plumbing consultancy, and you can browse pumps and parts in the shop.

FAQs

How many pumps does a hot tub need?

At least one that can do both circulation and jets (a two-speed pump), but most DIY builds do better with a jet pump plus a small circulation pump, and one extra pump for each water feature.

How many jets can one pump run?

Roughly 16 jets for a large pump with well-sized plumbing, based on about 10 GPM per jet. Check the pump curve for your pump and pipework, because the real flow is usually lower than the headline figure.

Do I need a separate circulation pump?

Not strictly, but it saves energy, is quieter, and is what an air source heat pump or gas heater wants. See how to add a circulation pump.

Can two pumps share the same pipework?

Yes, but jet and circulation pumps should be plumbed side by side (in parallel), not one after the other in series.

Does a bigger pump fix weak jets?

Usually not. Pipe size, the filter, the heater and the number of fittings decide the flow. See how to size a hot tub pump.

Got a question about your own setup? Drop it in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi