Why Do We Use Lead Free Solder?


Whether it be a repair on a water line in your house, or the installation of the piping on a new house, soldering is a common method used.

Copper pipes are very common in plumbing and have been since the 1960’s when galvanized pipe started becoming less popular.

Soldering is heating up a copper pipe to allow the low-melting point ‘alloy’ to form around it and the fitting being attached, creating a water tight seal.

So why do we use lead free solder? Lead has been found over the years to cause severe harm to our health and has been phased out. A potable water copper plumbing system utilizes a ton of solder to piece it all together and create a water tight seal, thus the need for no lead.

Even with the modern advancements in water supply systems, such as PEX and CPVC, the use of copper is still very much here to stay.

There is a lot more to learn about copper piping and the solder involved, so stick around to learn more!

Why We Use Copper In Plumbing & How It Relates To Solder

Over the last 100 years, there have been a few different ways water has been supplied to our households.

Lead Pipe

The earliest way was a very easy material to work with and malleable, and that was the lead pipe. The lead pipe that supplied water to the homes it served were increasingly becoming a problem.

Not for their durability, leaks, odor or anything of that nature, but because of the health effects it was having on the individuals using this system in their homes.

Death, was among the many reasons it eventually became obsolete and never to be used again in potable water systems.

What is “potable”? Potable is a word commonly used in the plumbing community to communicate water is safe for humans consumption. Potable water is what is required in all homes today. Non-potable water sources are found in areas like factories and industrial buildings etc. which consumption of the water is not readily available to us, keeping us away from the harm.

Lead pipe was phased out in the 1920’s and is so rare to find in homes now of days, that there may not even be any homes left with it.

Galvanized Pipe

Once we started to scramble to replace all of the lead piping that was being used in homes, we had to come up with an alternative to it, something rigid and strong and could effectively carry our water to us.

The solution was galvanized pipe. The pipe was a strong material and could be threaded. The threading process allowed for fittings to be attached by screwing it on, just like a water bottle cap goes over top of a water bottle.

The pipe was dipped in a zinc solution to create the galvanizing over top of the pipes. The reason this was done was to prevent things like rust and corrosion from occurring which would ultimately create failures and leaks as well as flakes of steel in our water supply, no thanks!

Often times though, this zinc solution was in a pot full of materials that were melted previously such as trace amounts of lead, making this an unsafe pipe to have in our homes.

Over time, the water would actually begin to leach some of the galvanized steel and it would get into our water supply and into our bellies.

Copper Pipe

Again, action had to be taken and a new form of water supply was desperately called upon.

Thus, copper pipe began to be the norm among households, and even to this day still gets installed into many homes among the United States and Canada.

Copper pipe wasn’t new at the time, and actually had been used since the 1930’s alongside galvanized pipe. It wasn’t until the 1960’s that it became the go to pipe for houses and businesses.

This pipe was not only a rigid material to work with and great to work with, but it also has a desirable look to it, that many people are actually wanting to leave portions of their water piping exposed.

Copper can actually be made into sinks and faucets as well and can create a very unique and luxurious look to it.

However, even though there were vast improvements made to the piping that supplied water to our homes and mouths, there was still one thing that hadn’t changed for a long time, and that was the solder used to connect the pipes and fittings together.

In fact, solder that contained lead in it was still being used up until the point of it’s ban in 1986. It’s crazy to me to think about how recently it was that we were still exposed to the dangerous and very harmful lead.

How Solder Can Affect Our Drinking Water

So to recap on what solder is, it’s an alloy with a low melting point that is used to connect copper pipe with a copper fitting.

Solder now of days is completely lead-free and is safe for us to consume the water that passes by it.

The reason solder affected our drinking water in the past is because of the way it allowed the copper pipe to be connected to the copper fitting it attached to.

The process of soldering goes like this:

  • The end of the pipe gets sanded down, cleaning it off from dirt and other impurities
  • Flux is applied around the end of the copper pipe and inside of the copper fitting. This acts as another way to clean the pipe as it is acidic in nature
  • Once the fitting and pipe have flux applied to them, they are pushed together and the process of heating up the pipe and fitting commences
  • With the flame circling around the circumference of pipe and fitting and heating them up, the low-melting point ‘alloy’ known as solder can be applied
  • For best results, the flame should be closer to the bottom of the fitting where the pipe ends on the inside of the pipe, and the flame facing towards the point of connection where the solder first begins to melt
  • As the solder is applied to the pipe, it melts almost instantaneously around the pipe and into the fitting completely getting drawn into where ever heat + flux was applied

Since the solder completely spreads out inside of the fitting and around the pipe, a small part of it will have contact to the water that will eventually flow past it.

This contact over time is what leads to lead soldering to become leached into the water supply and causing harm.

Because soldering occurs all throughout the house, the amount of total solder used is in large amounts, thus leaving us exposed to a lot of it and thus the reason for the lead-free solder to become introduced.

The Reason Leaded Solder Was Used Over Lead-Free

The reason lead-free solder wasn’t immediately used as galvanized pipe and lead pipe were beginning to become phased out is because of the lack of knowledge around it having contact with out water supply.

Since we weren’t yet aware of how harmful the solder could be, lead solder was still getting used frequently.

Lead solder is actually a preferred method of soldering in the joining together of materials and products that don’t come in contact with human consumption, such as RC cars and electrical work.

Lead is a heavier material that is easier to solder to pipe and has a stronger overall bond to it, thus keeping it a preferred method of use for so long.

Not to mention the cost of the solder that contained lead versus the lead-free alternative. The price of the lead-free alternative was actually higher than it’s predecessor.

Lead was even used in pencils up until 1978 when it was prohibited. The lead pencils were causing kids to become sick as they inevitably were chewing on them, as kids do with objects.

resources:

https://en.wikipedia.org/wiki/Solder

https://www.copper.org/environment/water/e_p_lead.html

https://www.tandfonline.com/doi/full/10.1080/02670836.2016.1220906

https://www.sciencedirect.com/science/article/abs/pii/0043135495000056

Tyler Takacs

My name is Tyler, I live in Ontario Canada and enjoy learning about common plumbing issues in the household. I have spent just over three years in the trades as a plumbers apprentice, but am now onto a less physical job. I still enjoy studying and learning about my own house's plumbing as well as finding ways to help others with their issues.

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