Caution: Homebrewers at Work

Whether or not you are a new brewer that has just started this hobby, or a seasoned brewer with years of experience, brewing safety should always be the first thing we consider when we start our brew day. Accidents are inevitable in any activity, but with a little knowledge and precautions we can help prevent brewing injuries from happening. Be warned, when bad things happen, they happen fast!

There is a long list of brewing injuries that I have seen over my 15 years of experience as a professional brewer and 11 years as a career EMT/volunteer firefighter. Most injuries are not life-threatening, but will put a hurting on you if you find yourself in that situation. Here are some useful tips for new and experienced brewers to think about while enjoying this hobby.


This topic always comes up for good reason. If you are intoxicated, even mildly, then your judgement is impaired and bad things can happen when dealing with boiling liquids, operating around open flames, or handling other potentially dangerous objects. I love to have a beer during my brew days, but keep it to a respectable level if you choose to do so. Other than the possibility of injuries, your beer may suffer as well if you are in a condition where mistakes are more likely to happen. Most accidents are preventable and caused by human error, being intoxicated will drastically increase these odds.


We all get excited on brew day, or sometimes we have just enough time to squeeze in a batch. Accidents often happen because we are rushing around or just aren’t paying close attention to what we are doing. Pay attention to what you are doing and your tasks, especially while around dangerous situations. Just about every brewing injury that I have experienced or seen over the years, homebrew and professional, was due to rushing around with a cluttered head. Knowing your equipment, how it is operated, the processes that you plan on using, and staying focused on your tasks will greatly reduce the risk of an incident from occurring.


Before you start your brew day you should always check your brewing equipment to make sure it is in safe working order. Check to be sure that all hose clamps, propane connec-tions, keg and/or fermenter pressure relief valves are free of debris and
working properly.


This second degree burn was caused when I wasn’t wearing gloves and was rushing to empty my kettle, grabbing the scalding hot bottom before I could stop myself. I had to soak my hand in cold water as it blistered over the next 24 hours to stop the burning pain.

Burns of all sorts likely make up the biggest percentage of serious homebrewing injuries. Brew day is full of hotside activity such as heating up brewing liquor, boiling wort, hot equipment surfaces, open flames, pumps and hoses moving hot liquids, and steam. In homebrewing, the most common types of burns we come across are first degree burns (minor superficial burn), and second degree burns (partial thickness burn). On rare occasion we may see third degree burns (full thickness burns), which end in an emergency room visit.

Some things to watch out for to prevent getting burned are:


These always happen when your back is turned or you look away. Whenever possible, keep your eyes on your boil. When you aren’t watching it, keep your distance from the boil kettle and your heating source. This will keep you out of harm’s way if a boil-over does happen and will allow you to handle the situation without panic. Another tip would be to use FermCap in the boil as it helps prevent boilovers from happening in the first place.

Use gloves for handling hot equipment:

This might seem like common sense, but even I have made this mistake more times than I’d like to admit, burning my hands and fingers in the process. This all could prevented by wearing safety equipment.

As a firefighter we teach that when you touch what might be a hot object or surface, to use the back of your hand with a single light tap. Your natural instinct when touching a hot surface is to close your hand which can cause further injury. By using the back of your hand with a quick light tap allows you to gauge how hot an object is without getting burned.

Proper footware:

All professional breweries I’ve been in require boots and often steeltoes in the brewing areas. Not only is there a risk of something heavy falling on your foot while brewing, but rubber boots will also prevent boiling wort that flows out of an open valve or boils over from scalding your feet.

Avoid splashing:

Brewers get into the habit of throwing things into the kettle when the time calls for it. Whether you are throwing in a bag of hops or trying to mix in extracts, there is a chance for splashback of hot liquids if you aren’t careful.

Be aware of your surroundings and keep your brewing space organized:

On several occasions I have turned around to have someone standing there, and have tripped over the propane gas line or equipment that was “in my way.” Always be aware of your surroundings, especially when near a flame or boiling liquid. Make sure the working area is clear and safe when introducing hot liquids to the area.

A mention on chemical burns:

Most of the chemicals that we use as homebrewers are safe to handle without much issue, however the most common type of chemical burns that we experience are of burns to the eyes. I have seen on several occasions a brewer drop something into a bucket of a chemical solution, resulting in the solution splashing up toward their eyes and face. While I could have just added a general “wear safety equipment” section, I want to drive this point home to wear safety glasses! I have witnessed this happen too many times with homebrewers as well as professional brewers with horrible consequences. Wear your safety glasses!

If you do somehow get chemicals in your eyes, flush immediately with water. This means planning ahead for eye injuries. In this situation, it’s best to call out for help while flushing your eyes with water. Remember to flush in a manner as to not to wash the chemical into the uncontaminated eye. Make sure that you know where your eye wash stations are, even if it’s just a bottle of water, sink, or garden hose.


Most of the time cuts and lacerations are not serious, and can be handled by holding pressure and applying a bandage. The main cause of deep lacerations in homebrewing involves glass carboys. These fermenting vessels are heavy, made of thick glass that are often wet and slippery, and can break easily if exposed to thermal shock (eg. placing hot liquids into a cold carboy, causing it to shatter) or dropped. When carboys do break they are sharp and extremely dangerous (I’ll spare you the images of these accidents).

When these type of accidents occur the common injury sites are the fingers, hands, and forearm section. These lacerations are often serious as it can cut into veins or arteries causing a significant amount of damage and blood loss. This may require professional medical attention. When handling glass, make sure that you have a firm grip on it and your walking path is clear of any debris to trip over. There are a few companies that offer safer carboy carrying devices that mitigate the risk of them slipping out of your hands from being wet or their awkwardly cumbersome shape.


We talked about burns by touching hot equipment or getting splashed with hot liquids already, but if care is not taken, there is also the possibility that kettles can get knocked over, spilling gallons of hot liquids creating a serious hazard. I have also met homebrewers that have slipped on random objects and fallen with a portion of their arm in the boil kettle causing severe injury. These type of burns are serious, and often preventable simply by slowing down and paying attention.

Another serious equipment injury that we come across are mill or auger injuries. I know this sounds obvious for most poeople, but keep your hands out of the cookie jar! There is no reason to stick your fingers in the mill. Once it grabs you, it’s safe to say that your brew day will be over. Unplug mills after use or if you have to service them for any reason. As we grow into this hobby we often like to upgrade our automation to make brewing beer an easier process. Moving parts always come with their own hazards, so pay attention.

ASPHYXIATION (Propane, Carbon Monoxide, Carbon Dioxide, &Dust Particles)

Asphyxiation injuries in the home-brew setting are extremely rare, but it does raise concern and requires a little thought and wise practices to prevent any incidents from occurring. Many homebrewers don’t have a lot of space when it comes to the hobby, and we work within the space that we have available to us to get the tasks done. For those brewers who decide to brew indoors, your best option is to use an electric heating source.

Milling hazards:

A word of caution on milling, or using ingredients with fine particles or powders, especially in a confined space or small rooms. While it’s rare to have an incident involving small particles on a homebrew scale, it is wise to wear personal protective equipment (PPE) to prevent any short-term or long-term lung damage. Usually a simple dust mask or an N95 respirator is enough to prevent any damage. Pretty much, don’t mill in a small room without breathing protection or proper ventilation.


The best recommendation is to use propane burners outside. Those brewers who insist on using propane burners inside or in their basements should be well aware of proper ventilation safety. Proper ventilation is the key to brewing indoors safely, as well as avoiding confined spaces. When using a propane burner, you want to make sure that the hoses are properly connected to the tank so they don’t leak propane into the room causing an explosion hazard, or a drop in oxygen saturation in the air. Normal saturation of oxygen in atmospheric air is between 20.8 and 21%, while OSHA (Occupational Safety and Health Administration) states that there is an oxygen deficiency once the oxygen levels reach 19.5% and below.

Propane gas (C3H8) has a molar mass of 44.10 g/mol, and is heavier than air, which has a molar mass of 29 g/mol (small variation depending on humidity). Propane has an Immediate Dangerous to Life & Health (IDLH) value that is close to its Lower Explosive Limit (LEL), which occurs at 2,100 ppm (parts per million), so OSHA rounded the IDLH number down to 2,000 ppm.

Carbon monoxide:

When you are correctly using the propane burner, two main byproducts produced are heat & carbon monoxide (CO). Carbon monoxide is a colorless, odorless, and tasteless gas that has a molar mass of 28.0 g/mol, which is slightly less dense than air. OSHA limits employees of an 8-hour shift to be in a carbon monoxide environment of 50 ppm or less. Exposure to 100 ppm or greater presents great health risk, or even the possibility of death. Some signs and symptoms that help indicate carbon monoxide poisoning include: Headaches, weakness, dizziness, nausea or vomiting, shortness of breath, confusion, blurred vision, and even loss of consciousness.

Carbon dioxide:

Another issue with small rooms, closets, or other confined spaces is the production of carbon dioxide (CO2) as a byproduct of fermentation. Carbon dioxide is heavier than air with a molar mass of 44.01 g/mol, and will sink to the ground. On average, for every pound of alcohol created, roughly 1.045 pounds of carbon dioxide are also created.

For example, if you ferment 6 gallons (23 L) of wort with an original gravity of 1.055 you should end up with close to 6% ABV, or 4.8% ABW, beer. With water weighing 8.33 lbs./gallon we can estimate the full weight of the batch by multiplying the fermenting volume by 8.33 by the specific gravity. In this case:

6 x 8.33 x 1.055 = 52.7 lbs. beer weight


52.7 x 0.048 ABW% = 2.5

This shows that 2.5 lbs. (1.1 kg) of carbon dioxide is created during fermentation. With 1 lb. (0.45 kg) of carbon dioxide occupying 0.2426 m3, or 8.566 ft3 (64 gallons/243 L), the 2.5 lbs. (1.1 kg) of carbon dioxide created in the 6 gallons (23 L) of 4.8% ABW beer should take up 21.415 ft3. Most of the time fermenters are placed in large areas with good ventilation that allows the carbon dioxide to dilute in the surrounding air. Proper ventilation and large areas of space should prevent the oxygen levels from dropping to unsafe levels that cause hypoxia. Don’t ferment in confined spaces without proper ventilation.

Carbon dioxide is a dangerous gas that claims the lives of brewers each year who are caught unprepared or unaware. In brewery settings we like to use the buddy system when working with large amounts of CO2. We let co-workers know what we are doing so they can keep an eye out if anything might happen. If you see a brewer down, call for help and further ventilate the room if possible. Do not rush in to help, as the area can still be at unsafe oxygen levels, creating two victims instead of one. The coal miners used canaries for the same purposes, because blackouts from a lack of oxygen can happen extremely fast. Again, this is less likely in a homebrew setting, but it is something to keep in mind.


Different styles of beer call for various volumes of carbonation. Average beer CO2 saturation for most styles are around 2.60 to 2.70 volumes, with a few styles at a higher level of 3.0+ volumes of CO2. Soda is bottled around 3.0–3.2 volumes of CO2, which is close to the top limit of CO2 saturation that we use in bottles.

While working at several breweries over the years I have dealt with different bottle manufacturers, and each bottle manufacturer has their own process, equipment, and specifications that they use to produce their product. Just like each maltster is unique to their craft, the same applies to glass manufacturing. Most of the time we were only ordering 12-oz. and 22-oz. (350- and 650-mL) bottles, which is what most homebrewers use to bottle condition their beers.

To prevent bottle bombs you need to do a few main things. If you plan on adding priming sugar, you need to make sure that the beer has reached terminal gravity and no more fermentable sugars are left. When you do add the priming sugar, do the math and measurements twice, and dose once. Precision is recommended here. I have seen many 12- and 22-oz. (350- and 650-mL) bottles explode on the bottling lines at around 3.3 volumes depending on manufacturer. Try to use quality bottles, and know exactly how much fermentable sugars are being dosed into each bottle to create the target CO2 volume to prevent a flying glass shrapnel incident. Bottles will break, so be sure to wear your safety glasses, or a face shield when using counter-pressure bottle fillers.


Just like glass bottles, not every vessel is created equal. Whether you are using a 5-gallon (19-L) plastic bucket, glass carboy, or an expensive stainless steel conical fermenter, make sure that it is in working order and free of obstructions in the blow-off tubes and/or pressure relief valves (PRV). I have seen lids explode off of buckets, carboys shatter, and the top of a 100-barrel fermenter explode due to high pressure, a clogged PRV or airlock, or lack of one altogether.

Kegs are also pressurized vessels that need to be addressed, as we have seen deaths in the industry over the past couple of years. Some kegs like the Cornelius soda kegs have PRV’s that are easy to relieve pressure, while other kegs like Sanke kegs need the coupler to be attached to have access to the PRV. Whatever vessel you choose to ferment or package your beer in, make sure that you know all of its specs, check that it’s in working order with every use, and do not go over the recommended PSI.

These type of injuries can be deadly and catastrophic . . . The London Beer Flood of 1814 is a great example of the devastation that can happen (on a much larger scale).


Every once in a while, we either fail to follow the proper chemical directions, or make a foolish mistake by not paying attention to what we put in our mouths. I have only seen this happen two or three times, but it does happen. Follow all recommended chemical instructions, as well as keep your food or drinks away from your workstation. If for any reason you do happen to ingest any chemicals, contact the Poison Control Center in the US at 1 (800) 222-1222 immediately. They are open 24 hours a day, 7 days a week, and will be able to give the best, and most direct advice tailored to your specific situation, as well as notifying your local emergency dispatcher to give them a detailed report and their recommended medical direction.


Slow down, relax, and have a home-brew if you choose to do so, but pay attention to your surroundings and what you are doing. Keep a clean work area, measure twice, dose chemicals once, ventilate confined spaces, wear safety equipment, keep food and drinks out of work areas and away from chemicals, watch those hot liquids, and keep those fingers out of the mill to help make a successful and injury-free brew day.

Issue: September 2018