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Reduce the risk of Legionnaires' disease in your home

Nine recently confirmed cases of Legionnaires' disease in Hopkins, MN reminded me of an old blog post that I thought would make for a timely re-blog, along with some updated information. First, here's the story about the recent cases in Hopkins: As mentioned in the story, Legionnaires' disease resembles a severe case of pneumonia and is spread by inhaling the fine spray from water sources containing Legionella bacteria. In your home, the source of that bacteria could be your water heater, especially if you turn your water heater temperature down to the "vacation" setting when leaving for extended periods of time. The people who are most at risk for Legionnaires' disease are those over 50, smokers, or those with certain medical conditions.

Scald warning

According to, legionella bacteria can grow at temperatures from 68° F to 122° F, but the ideal growth range is between 95° F and 115° F. When it comes to preventing legionella bacteria growth, hot water is better. Legionella bacteria cannot multiply at temperatures above 122° F, and are killed within 32 minutes at 140° F. So crank up the water heater as high as it will go, right? No, of course not. That would create a scald hazard. Water heater manufacturers put a warning on water heaters saying the water temperature should not exceed 125° F to help prevent "severe burns instantly or death from scalds". Their words, not mine.

So what's the perfect temperature for your water heater?


Unfortunately, there's no simple answer. The American Society of Sanitary Engineering Scald Awareness Task Group released a white paper many years ago on this topic, which essentially says that there is no perfect temperature to set your water heater to. Part of the reason is that traditional tank-style water heaters don't keep the water in the tank at an exact temperature; there is a temperature "band" that tank water heaters maintain. At the beginning of a heating cycle, a water heater set to 120°-ish might start at 115° F, and might get up to 125° F at the end of its heating cycle. There's more to it than just that, but the point is that water heaters do not produce constant temperatures.

If the water in a tank is kept below scalding temperatures, there is a potential for Legionella bacteria growth. Ideally, the temperature in a water heater tank should be cranked way up to 140° F or higher, but now we're back to the scald hazard thing. One solution is to have a hot water tempering valve installed for the entire home.

This valve would be installed right at the hot water outlet of the water heater. It would allow the water heater to be cranked up to a scalding 140° F, which would be sufficient to kill bacteria and would extend the capacity of the hot water tank, while at the same time reducing the temperature of all of the hot water throughout the house. Click the following link for more information about these devices: . While these devices won't guarantee safe water temperatures at every fixture, they'll get you a lot closer.

If you want more hot water out of your water heater and you want to reduce the risk of Legionella bacteria growth, hire a plumber to install one of these mixing valves at your water heater and turn the temperature up on your water heater. I should also mention that point-of-use thermostatic mixing valves should ideally be installed at the faucets for the highest level of safety... but I'm pretty sure I've never seen a home fully outfitted with those.

Author: Reuben SaltzmanStructure Tech Home Inspections


Updated home inspector training advice

Many years ago I wrote a blog post giving home inspector training advice to future Minnesota home inspectors. The purpose of that post was to give a thought-out response to people who emailed or called asking for advice on how to become a home inspector. At that time, I'd receive two to three inquiries per month. Now, almost five years later, I receive about two to three inquiries a week. To write that blog post I interviewed several other home inspectors here in Minnesota, asking about how they got started in this profession and what home inspector training advice they would give to someone just getting started in this business. Some of the same advice applies today, but a lot of it has changed.  There are also many other questions that I regularly receive that weren't addressed in that blog post, so I'll cover them today.

To write this post, I went over my emails from the past several years to see what other advice I had given to people looking to get into this profession, and I've added a few more pieces of info.

Q: What's the best training school for home inspectors?  

A: I don't know. I've only been to one home inspector training school, and it was over twelve years ago. I took a weeklong course and I wasn't at all impressed, so I won't share the name of the school. I've heard good things about The ASHI School from home inspectors who have gone through that training, but I have no firsthand experience with that school. Back in 2004 and 2005 I took several Building Inspection Technology classes through North Hennepin Community College, but the BIT program has been stripped down to only four classes now, three of which have very little to do with inspecting single family homes. Because of this change, I no longer recommend the BIT program to people looking to get into the home inspection profession. Time and money would probably be better spent going through a school dedicated to teaching the home inspection profession.

Just be aware that a home inspection school is only the tip of the iceberg when it comes to the amount of knowledge that one should obtain before getting into this profession. Anyone doing home inspections on their own should do a lot of studying on their own and get as much hands-on training as possible.

Q: How can I get hands-on home inspection training?

A: Home inspection schools often include some hands-on training, but that's only the beginning of the amount of training needed for this profession. To get real-life home inspection experience, one must attend home inspections with experienced home inspectors. The American Society of Home Inspectors (ASHI) allows home inspectors who are willing to take other home inspectors along on inspections, for the purpose of training, to register as a Parallel Inspection Guide. This is a publicly available list, which can be viewed here: My name is on that list, but nearly every home inspection that I do is also done with a new inspector from my company, so I do very little training for home inspectors outside of my company. Some home inspectors charge a fee for this training, some don't.

Many home inspectors get "funny" about allowing ridealongs because they're afraid that they'll be training their competition. This is partly true, but in a larger market like the Twin Cities, having a few more home inspectors enter the business won't ever make a bit of difference to me. Thousands of houses are sold every month here in the Twin Cities.  If a new home inspector enters the market and instantly starts doing two home inspections a day, would I ever feel that impact? No way. I've found that I learn a lot while teaching others, however. If someone is going to enter this business, I'd rather they be a competitor who does things the same way that I do and charges a similar fee; not some hack inexperienced person who charges $200 and gets their home inspections done in an hour.

Another way to get hands-on home inspection training is to get to know other home inspectors in your area through local chapter meetings. The ASHI Heartland Chapter meets once per month, and we all get to know each other through these meetings.

Q: Do you hire and train people without home inspection experience?

A: Yes, and I think that I speak for most owners of multi-inspector companies when I say that the ideal job candidate will be an experienced home inspector with excellent communication and writing skills who is willing to learn new ways of doing things. A less attractive candidate would be someone with no home inspection experience, but someone who has experience in one or more trades, has attended a home inspection school and has excellent communication and writing skills. A less attractive candidate would be someone who has only attended a home inspection school and has excellent communication and writing skills. An even less attractive candidate would be someone with no trade experience and no formal training, but still has excellent communication and writing skills. Take away the communication and writing skills and they wouldn't even be a candidate.

Q: How long does it take to train a new home inspector?

A: It depends on experience. I've found that the shortest training period I'm comfortable with for new inspectors is about four months, and that's assuming the person is already knowledgeable in all areas of homes.

Q: What are the physical requirements?

A: Less than most trades, more than most desk jobs. My humble opinion is that one must be comfortable walking roofs with at least a 6/12 pitch, be able to carry a 28' extension ladder, be comfortable climbing around in attics, into and out of window wells, under sinks, and crawling around in crawlspaces. Those aren't requirements to enter this profession, and home inspectors are not required to walk roofs or climb through attics, but I think that anyone who is unable or unwilling to perform those tasks would have a very hard time establishing themselves in this profession, partly because there are plenty of other people in this profession who are willing and able to do those things.

Bill checking out a roof cap Tessa in attic

Q: What are the licensing requirements in Minnesota?

A: There is no such thing as licensing here in Minnesota. Most states have it, we don't.

Q: What study materials do you recommend?

A: For future home inspectors anywhere, I recommend the following:

  • The National Home Inspector Exam Home (NHIE) Inspection Manual and the NHIE Study Guide. This exam is used in approximately half of the states that have licensing requirements and is used by ASHI as a prerequisite to achieving "ASHI Certified Inspector" status. Note: the ASHI Store sells the Study Guide and Manual as a set for $99.
  • The Prescriptive Residential Deck Construction Guide - to paraphrase myself, this should be required reading material for anyone who builds or inspects decks. The building code is quite difficult to fully follow and understand when building a deck, but this guide has taken all of the building code requirements that are scattered throughout the IRC and put them into one location.
  • History Note about service drop heightElectrical Inspection of Existing Dwellings - this is the home inspector's Bible for electrical inspections. Every home inspector ought to own this book. This book should be read, re-read, and kept handy for reference. Even for those well-versed in electrical codes, this book contains many helpful electrical history notes, such as the example shown at right, used with permission.
  • Code Check books. There is no other quick-reference book that makes it easier to find the exact code requirements you're looking for. These books reference national codes which are frequently changed at the state level, so they're never 100% applicable, but they at least make it quick and easy to know where to look, and the illustrations are fantastic.

For future home inspectors in Minnesota, get familiar with the Minnesota codes.

There is nothing that is Minnesota-specific related to electrical; we adopt the entire electrical code.

As ongoing reading materials for all home inspectors, experienced or not, here is some of my favorite reading material for ongoing education:

  • The ASHI Reporter - ASHI's monthly magazine. ASHI members get a free subscription, but the digital version of the magazine is free to everyone online.
  • Building Science - this is a great resource for building science information. Subscribe to their newsletter at the bottom of their homepage.
  • Energy Vanguard Blog - great blog about insulation, HVAC, building science, and the like. Go halfway down the page to subscribe.
  • The Journal of Light Construction - I get the paper edition, but their website has lots of great info as well.
  • The Family Handyman - this is also a great magazine for every motivated, handy homeowner. Again, I get the paper edition, but their website is excellent and seems to dominate search results related to all types of home improvement projects, and for good reason.

Author: Reuben SaltzmanStructure Tech Home Inspections