In the next five minutes or so, I'm going to answer a fundamental question, which I'm asked about all the time and that is after an unexpected water damage event at your property, what's the probability that you're going to end up with a mould problem? I'm going to cut straight to the answer here. You need to answer three questions. That is, how much water was present? Was it a little bit, or was it a lot? How long was the water present inside your property? Was it minutes, hours or was it some days? And there's a really important question because so many of my clients are going through insurance related water damage claims, and often the time from the initial wetting event to when someone comes to assist the property, or importantly, when someone comes to do make safe works is often a lot longer than hours or even a few days.

So that's something you all need to be aware of. And then the third question I need all of you to consider is, what type of water caused the wetting event? And you might be thinking, well, it's water, it's wet and it's causing problems for myself. I don't want to get mould. You need to know the difference between the types of water, because it has an impact on the likelihood that the wetted building materials are going to go on and cause a mould problem. What do I mean by that? Well, clean water is one type of water. Grey water is another type of water, and Black water is yet another type of water. And you might be thinking, well, hang on, you haven't explained what the differences are. Well, I'm going to go through this in today's live stream. The reason I wanted to talk about this is that we obviously have a lot of erratic weather patterns ahead of us, certainly for us in Australia, this is true.

So the question this week is how to stop the spread of mould this wet and warm summer. To answer that, I want to talk and look at this issue of the different types of water. So category one water, for example, is from say an overflowing bathtub that is predominantly clean water. Whereas grey water has a combination of different biological and potentially chemical contaminants. So there is a higher nutrient content and typical examples are overflowing or broken or misfunctioning dishwashers or that sort of thing, washing machines. So if that type of water wets your carpet unexpectedly, that is more serious than a broken pipe or bathtub overflow, and the most serious type is black water. This contains harmful bacteria, yeasts, and fungi, and the problem with this and some good examples are rising sea levels, rising flood waters where rivers or streams enter a property or standing water. Think of box guttering for example, or other problems with your guttering or standing water under a building where it can't escape into the storm water drain or sewage backflow through the toilet.

And if that affects your property, that is really serious. I also want to talk about something called water activity, and you'll see it down the bottom of this slide. Water activity is related to this concept of water content. I'm going to give you a demonstration here because I think I need to make this point very clearly. This is a moisture meter. Now, these are easy to get and usually your water restoration technician, or even your insurance assessor is going to have one of these devices, and if we can imagine that this sponge represents anything porous inside your home, which might've gotten wet from one of these category, one, two or three events, or imagine that this is like the plasterboard wall behind me in my office. Now this is porous to a greater or lesser extent and most of the building elements in your home are also semi-porous.

Now when your water restoration technician comes to potentially dry out your property, you need to be very aware that there is a big difference between water content and water activity, and I'm going to describe that by this demonstration. So imagine that this is something inside your property, which has become wet. I have lightly wetted this sponge. When I put the moisture meter into this, this is measuring the water content. And as you can see, it's registering a roundabout 56%. Now, if you can imagine a glass of water, water is free flowing. So this is the concept of water activity. When water is taken up by a semi-porous or a porous building material, it gets caught inside that material and you need a great deal of energy to extract that water.

So I wanted to draw your attention to this very significant fact of difference between water content and water activity, because many water damage restorers will tell you that as long as the percentage is under 15%, you have nothing to worry about with regard to mould. I'm here to tell you that that is absolutely false and misleading information. It's very misleading because of this concept of water activity, because different bacteria, yeasts and fungi have different requirements for water and that relates to their water activity. Think of things like dried figs and nuts for example, they're pretty dry materials, aren't they, but there is still sufficient moisture in a lot of those materials to support microbial growth. So we need to make sure that following a water damage event to our buildings, that they are definitely dried thoroughly and that gets me back to closing out this short discussion about water activity, that even with heavy water content and activity, there are ways for you to prevent mould growth.

And we are going to go through my top 10 methods that you should consider if you are affected by water damage in an unexpected way. We will take these, not in any order of priority, obviously opening doors and windows is important, but if there is a significant storm front outside, opening doors and windows is not really going to improve the evaporation of the water. So you need to use your common sense here. But obviously dry wet surfaces treat any emerging patches of mould, just don't look at it and hope it goes away. Definitely use mechanical ventilation. Your heating system and air handling system is an important tool to use in solving indoor water damage problems because many of them contain dehumidifying capacity as well, because the whole point is that you want to reduce the indoor humidity as quickly as possible. Also, if your porous property like curtains or clothing have become water damaged, you want to wash them using your washing machine operating at a high temperature.

Now, I'm asked all the time, why use a high temperature? Well, the research is in the literature showing that a high water temperature improves the reduction of harmful microbes that can remain viable on clothing after it has been washed. Where does this evidence come from? Well, it comes from hospital laundry and microbiological tests on that. So what's good for the hospital is good for you and your home contents that is porous-like fabrics and materials. So dry them on or wash them using the hot cycle. The next thing is to also consider regular cleaning and maintenance of your washing machine. Other publications in the research literature show that often the containers used for putting the washing powder in develop biofilms in them. So it's important to regularly wash those out so you don't re-introduce that into your water. Now you want to look for odours as well.

In the last couple of weeks, we've talked about microbial volatile organics or the smells that are given off by growing fungi. You want to get rid of these and look for these as well. Certainly in your home you want to improve drainage around the building and perform regular maintenance around guttering, bathrooms and kitchens. So along with prevention, it is very helpful to learn how to observe and identify mould. Well, most of us can easily identify mould, but questions I'm often asked is, does it always need to be visible to be a problem? And I can definitely tell you that mould can be a serious problem, even if you can't see it, and the reason for that has to do with this concept of water activity. So just because the outside of your plasterboard might be relatively dry to the hand touch doesn't mean that the insulation within your wall or your ceiling cavity or even your floor insulation, that could be water damaged or water logged just like water gets into this sponge.

So this concept of water activity is very important. So definitely consider what might be behind plasterboard up in roof cavities or under floors and that also extends to under waterproofed membranes in wet areas like bathrooms and showers. And if you can smell something, you probably definitely have a problem and that is related to this concept of volatile organic compounds. So identifying hidden mould before it becomes a problem is an absolute key. Now, many people call up and say, "Listen, I don't own my property. I'm renting and I've got a problem." And similarly, many landlords and property managers ring me up and say, "Tenants are complaining about water damage and mould. Is it really the responsibility of the landlord?" So I've put together this quick slide summarizing the roles and responsibilities of both parties. Now, my mould advice for tenants and landlords is as follows. If you're a tenant, you have an obligation to keep your property clean.

You should alert the landlord or property damage immediately about any damage that you note. You need to use any exhaust fans in the bathroom and also in the kitchen whilst cooking to reduce the level of water vapor and humidity build-up inside the property, and obviously if there is a water damage event, the owner's responsibility is on you to do something about it, not just ring through with a problem and wait for someone to attend, take some proactive action and dry out and treat the wet carpet as quickly as possible, put some extra towels on it, open the doors and windows to facilitate evaporation. But if you're a landlord, you definitely have a requirement to act quickly on maintenance requests. That definitely means following up with the property manager, especially if you're discovering that there are multiple emails being sent to you or your property manager with tenants having some problems. You do need to investigate these thoroughly.

It is up to you to maintain the building in a reasonable state of repair and you obviously have to ensure that the building meets health and safety requirements. So in a sense, both tenants and landlords are responsible for mould prevention, but in different ways. So in summary, remember, how long was it wet? What type of water was it and how much water was present? These are the three key considerations which you need to consider. And then it is plain common sense, maybe with some mechanical and physical controls to make sure that mould doesn't become a problem. And whether or not you believe in climate change or not, we are living through periods of time when weather is erratic and that variability in rainfall and different temperatures have an impact on when a building will be potentially subjected to unexpected water ingress. In any case, as I say, each week, if you have enjoyed this live stream, follow and subscribe on any of my social channels. Stay safe, have a great week, and I'll see you next week. Bye for now.