How to Clean Beer Lines in Your Pub

Last updated: 26 June 2026

Most pubs don’t clean their beer lines properly — and it’s costing them thousands in stock loss every year without them even realising it. Dirty lines breed bacteria, allow product to sit stagnant in the pipes, and create a breeding ground for waste that never shows up on your till. The worst part? Your brewery stocktaker won’t catch it. A 1% stock loss on wet sales quietly costs a typical pub £3,000–£5,000 a year, and poor line cleaning is one of the biggest culprits. This guide walks you through how to clean beer lines properly, why it matters to your bottom line, and what equipment you actually need — not the stuff the wholesaler wants to sell you.

Why Clean Beer Lines Matter to Your Profit

Here’s the thing nobody talks about: dirty beer lines don’t just taste bad — they hide stock loss. When product sits in a line for days without being pushed through properly, you get bacterial growth, product separation, and eventually oxidation. That’s waste that never shows up as a spillage or a pour-down — it just vanishes into a pint that tastes off and a customer who doesn’t complain but doesn’t come back.

I was running my own pub on spreadsheets for years, and my draught margins were terrible. I couldn’t work out why. I’d dip the casks, log the pints sold against till data, and the numbers still didn’t match. Turned out my lines were thick with biofilm — the bacterial slime that builds up inside pipes. I was losing product quality and couldn’t even see it happening. Once I started a proper weekly clean routine and logged each one in a simple record, my variance went from guesswork to a number I could trust.

The real cost is in wet GP by line, not a single headline stock figure. Spirits hide losses in over-pouring — a free-poured 25ml is often 32–35ml. Draught hides it in poor cellar temperature and bad line cleaning waste. Most stock “theft” is actually measurement error and forgotten wastage. Clean lines solve the measurement part. You get clearer product, fewer complaints, and a clearer picture of what you’re actually selling versus what you’re losing.

How Often Should You Clean Beer Lines

The honest answer depends on your product mix and volume, but here’s what actually works in a busy UK pub:

• Keg lagers and bitters (high-volume lines): Clean weekly. These lines see constant throughput, but biofilm builds fast in the cool cellar environment.
• Real ales and cask products: Clean fortnightly if you’re changing casks regularly, weekly if a cask is sitting for more than a day between pints.
• Craft kegs and slower-moving products: Clean before you connect a new keg, even if it’s only been two weeks. Dead product breeds bacteria.
• Guinness and nitrogen-poured products: These need weekly cleans because the nitrogen creates a different bacterial environment.

The rule I follow: if you’re not confident the pint tastes the same as it did three days ago, your line needs cleaning. Most busy pubs move enough product that weekly makes sense. If you’re quieter, fortnightly is enough — but don’t skip a clean just because you’ve been quiet. A slow line that hasn’t been touched in ten days is a health risk and a stock loss waiting to happen.

Essential Equipment You Actually Need

You don’t need much, and you definitely don’t need to spend money on an expensive line cleaning machine unless you’re running 20+ taps. Here’s what actually works:

• Line cleaning kit (bucket with taps and connectors): £15–30. This lets you isolate a line and push cleaning solution through it without breaking the whole system. You can get them from any beer wholesaler.
• Line cleaning solution: Use the product recommended by your brewery or wholesaler for your product type. Draught lager uses a different cleaner from real ale. Don’t cheap out here — wrong cleaner leaves residue and flavour taint.
• Hot water: You need it to be hot enough to kill bacteria but not so hot it damages the lines. 60–65 degrees Celsius is the sweet spot. A kettle works fine for smaller pubs.
• Bucket or basin: To catch the cleaning solution and dirty water coming back out of the line.
• A simple log sheet or notebook: Write down what date you cleaned each line, which cleaning solution you used, and whether you noticed any blockages or off-taste. This becomes your evidence that you’re doing it properly — and it’s essential if anything goes wrong.

That’s it. You don’t need a fancy automated rig. You need discipline and a routine. Most of the stock loss I see in pubs comes from inconsistent cleaning, not from lack of equipment.

Step-by-Step Cleaning Process

Before You Start

Make sure your cellar is tidy and the tap you’re cleaning is not in use. If you’re cleaning draught lager, don’t do it during service unless you have a backup tap. If you’re cleaning a real ale tap, pick a time when you’re unlikely to sell from it — a Tuesday morning is ideal.

The Actual Clean

The most effective way to clean beer lines is to push hot cleaning solution through the line under pressure, then flush thoroughly with water, and finally push fresh product through to clear residue. Here’s the process:

1. Disconnect the line from the keg or tap. This is usually a simple twist or ball connector, depending on your setup.
2. Connect your cleaning kit to the line. Make sure all connections are tight — you don’t want cleaning solution spraying everywhere.
3. Draw hot water through the line first. Push about a pint’s worth of hot water (no cleaner) through the line into your bucket. This softens the biofilm and loosens debris.
4. Mix your cleaning solution according to the bottle instructions. Don’t guess the ratio — wrong concentration wastes time and leaves residue.
5. Push the cleaning solution through the line slowly. Take 3–5 minutes to work it through. You’re not racing. Watch the water coming out — it will be black or brown at first, then gradually clearer.
6. Leave the solution in the line for 15–20 minutes if you’ve got time. This kills the bacteria that just hot water alone won’t shift. If you’re in a rush, 5 minutes is better than nothing.
7. Flush the line with hot water again. Push at least a couple of pints’ worth through. Keep flushing until the water coming out is completely clear and has no chemical smell.
8. Reconnect the line to the keg or tap. Make sure the connection is secure.
9. Pull a pint and check it. It should be clear, with no off-taste or cloudiness. If it smells of cleaning solution, flush some more.
10. Log the clean in your cellar record. Date, time, which line, which cleaner. One line, one entry.

This whole process takes about 15 minutes per line if you’re not rushed. It’s worth doing it properly.

What to Do If a Line Is Really Gunked Up

Sometimes you’ll open a line and the cleaning solution comes back black or there’s a blockage. This usually means the line has been neglected for weeks. Here’s what to do:

• Push hot water through more aggressively. Use a bit of pressure.
• Let the cleaning solution sit in the line for 30 minutes. Really nasty biofilm needs time.
• If there’s a physical blockage (nothing comes through at all), you might have a hop debris or protein buildup. You might need to disconnect the line at both ends and soak it in a bucket of hot cleaning solution overnight.
• If this happens regularly on one line, the line might be kinked or damaged inside. Check with your wholesaler — it might be time to replace it.

Common Problems and Fixes

Pint tastes soapy or chemical even after flushing. You didn’t flush enough. Keep running water through until you can’t smell anything. The water should run cold and clear. If it’s still off, pull a few test pints and pour them away. Better to waste one pint now than sell soapy lager all night.

Nothing comes through the line. You’ve got a blockage. Check the connector is tight, then try pushing from the other end if possible. If the line is completely blocked, you need to soak it. Disconnect at both ends, submerge in hot cleaning solution in a bucket, leave for two hours, then try flushing again.

Pint is cloudy or has bits in it. You’ve got debris in the line. This usually happens if you’ve just changed a cask or keg. Pull a few pints away and try again. If it persists, the line needs a clean.

Pint has lost its head/carbonation. Your line is too warm. Check your cellar temperature — it should be 13–15 degrees for most draught lager. If it’s warmer, you need to cool the cellar or insulate your lines. A warm line loses carbonation and product quality.

Why You Need to Log Your Line Cleans

This is the part most pubs skip, and it’s the part that actually saves you money. When you log a line clean, you create evidence. You know exactly when the line was last cleaned, what cleaner was used, and whether there were any issues. Over time, this log becomes your early warning system.

If a line keeps getting blocked after two weeks, you know you’ve got a product issue or a line issue — and you can investigate. If your pint quality drops and you check the log, you can tell whether it’s been too long since the last clean. If your stock variance is bad, you can cross-reference your line cleaning log against your sales data and spot where the waste is happening.

I kept mine in a simple notebook in the cellar — one line per row, date and time. Took 30 seconds to write. But when my wholesaler asked me to prove I was cleaning lines properly, I had the evidence. When I was training a new cellarman, I could show him exactly what the routine was. And when my stock variance improved, I could point to the exact week I started doing it properly.

If you’re serious about tracking this properly, StockTap pub stock app has a cellar management screen built in where you can log every line clean, cask dip, and temperature check in one place. But a notebook works too if you’re consistent about it.

The key is: you can’t manage what you don’t measure. A line clean log is your measurement system. It tells you whether your routine is actually working or whether you’re just going through the motions.

For more information, visit SmartPubTools.