Water harvesting system

My father put in a water harvesting system when he built his house twenty years ago. It still seems to work. Last time I visited, I helped my mother change the filters and clean out the gutters. Actually we should have done that the other way around. While cleaning the gutters, a certain amount of crap ended up washing down the gutters, and straight into the nice clean filter, so if you ever find yourself cleaning a water harvesting system, clean the gutters first!

​Three drains from the house, and one from the garage to the right, all come into one gutter. This then heads through a drainpipe into the filter butt.


Water goes through a grill to catch leaves and large debris, then a felt filter bag lined with a nylon gauze bag. The filter butt can take something like 100 litres, which quickly fills up if it is raining heavily since the roof has a large area, and it takes time for the water to get through the filter. Another piece of advice: it's a good idea to change the filter when it has not rained for a while, then it is a lot lighter.



When you don't need any more water, the large yellow pipe to the right of the filter butt can be put onto the drainpipe to bypass the filter. In fact when changing the filters, we should probably have put the bypass pipe on.

Filtered water then goes into a tank under the garage. There are two tanks, one being filled and the other supplying water to the house. You can choose which tank to fill by putting the hose into it, and the red taps will choose which tank is supplying water.

Wonderfully low-tech!

You can see how much is in each tank with these two old washing-up liquid bottles, filled with sand, which have floats attached to the other end of the strings.

Detailed calibration has been added.

An electric pump draws water from the tanks, either on demand from a float in a tank at the top of the house, or at the flick of the "over ride" switch.

From the pump the water goes through a chamber with a purification tablet on the left, then another filter on the right.



The pipes then run along the wall to another clearly laid-out junction where the harvested rain water can be switched off, and mains water can be switched on instead. The pipe goes into the house and up to a water tank above the bathroom, which has a ballcock that activates the pump when more water is needed.


This system still works after twenty years, providing most of the domestic water. There are a couple of separate taps of mains water in the house for drinking and cooking. I particularly like the layout and simplicity of this system, and if anything did go wrong with it, any handyman could quickly work out what was wrong and how to fix it. Financially it has probably not paid for itself, since their water is relatively cheap, and in fact my Dad admitted it was a bit of folly, but I'm sure he enjoyed making the system and was very satisfied to see it work.

It does provide some insurance against water shortages, which may now happen with increasing frequency, in and amongst the increasing floods! In many areas there is a cheap, regular and safe supply of water, and harvesting your own water is probably a low priority if you are building on a budget. Rain water harvesting is now mandatory in some Indian and Australian states, and many places around the world offer financial support for people harvesting water. And if you are building on a plot a long way from the infrastructure then a rain water harvesting system could save money.

Drip drip drip

I already mentioned pools of water and houses and the question not being if it will happen, but when. It seems a bit soon to get another one, and a little inconvenient that it was on a Sunday when I had to work.

When I was making breakfast I saw the small puddle and the drips coming from the ceiling in the utility room. The utility room is directly under the bathroom, so that's where any water is going to end up. Although it doesn't have much respect for a house free of fungi, water does at least obey the laws of gravity.

The first reaction was to call the plumber. Actually the first reaction was to get a bucket for the drips and a cloth for the puddle as it still hadn't got very far. Also, since it was dripping quite slowly, I thought we should let the plumber finish his breakfast.

I finished my work early enough that the plumber was still working, searching for the source of the leak. When I spoke to him on the phone, he hadn't found it, and was about to give up and go home. He said the water was not coming from the bath or any leaks in pipes there, but from the wall between the bath and the boiler.

Thinking about the mystery on my way home, like a Poirot of plumbing, it increasingly seemed that the ventilation system was the problem. In the process of exchanging heat, the ventilation system takes a lot of water out of the air, which must find its way through a drain out of the house. This seemed the most likely source of the water.

The night before had been the first below freezing, and I wondered whether the outside drain from the ventilation system had frozen over, stopping the water from escaping. Of course the temperature had only just dipped below freezing, so it wasn't cold enough for pipes to freeze, and there had not been enough time for a dam of water to build up and get through the ceiling.

When I got home, the first thing I did was look at the drain as it leaves the house on the East side. There was no ice there. In fact the drain pipe itself was dry.

The plumber showed my the pipes above the utility room when I got into the house, and the one that water was dripping down the outside of. We went upstairs to the boiler, which was installed by different tradesmen and was not really his responsibility. There were pipes coming in from the external heat exchange units for the boiler, and the air conditioner that we don't use. There were just two pipes for each: a supply and return for the coolant. No drains.

I then suggested the room upstairs, which he had had nothing to do with, and was unaware of. Above the bath is the machine room with the solar power conditioners and the ventilation system.
And there was the smoking gun. Or at least the dripping pipe, and a pool of water underneath the ventilation system.

The pipe coming out of the ventilation system had come out of the drain in the floor. It had not been fixed in there, but was just pushed in, the ventilation "experts" no doubt hoping for the best. I go into that room about once a month, and it could well have been knocked out when I was vacuuming the floor last time I was in there a month before. Water had been slowly dripping onto the floor, gradually increasing in flow as the outside temperature dropped. As it found its way down past the bath, following the pipe, it would gradually have evaporated back into the house. For the last couple of nights, as the temperature dropped to around zero and the amount of moisture coming out of the air in the house increased accordingly, more or the moisture got to the puddle above the ceiling of the utility room, and in the morning it finally got through the drywall. In fact the dry wall was now a wet ceiling.

It's a good thing we'd just used drywall for this room rather than a plastered and painted ceiling. A screw driver is enough to take a panel off, and it can easily be replaced without needing to call in a procession of tradesmen. The drywall panel is now propped against the wall to let the ceiling dry out, and I can put it back again in a couple of days without having to call the plumber out again.

No more left over water left over

When you have a house, you know that sooner or later you are going to find a large pool of water somewhere. It may be dripping through the ceiling, trickling down the wall, or being sucked up by some cardboard boxes on a linoleum floor. Ours came rushing out of the washing machine, onto the tiled floor of the utility room, and then into the storeroom next to it, which has been cleverly placed a step lower down.

Washing machines are not supposed to let you open the door when they have water in them, and are not supposed to have water in them when they let you open the door, so we called the washing machine man in. Luckily the washing machine is still under guarantee, although we have had it a few years and brought it from our old house. The washing machine man came and declared that it was the fault of the plumbing. He demonstrated this by taking one of the pipes out of the top of the washing machine, and showing that water was dripping from this when the tap was switched off.

As in many cases, Japanese plumbing demonstrates both extravagance and frugality, making up this country's confused position as a home of both energy efficiency and resource squandering. Japanese baths, sweeping generalisation notwithstanding, are very large, using a lot of water and heat. On the other hand, they are not filled every day: the washing takes place outside the tub, so just a little topping up and reheating is necessary. Also, it is normal practice for the water from the tub to be used in the early cycles by the washing machine, recycling both the heat and water. Traditionally, I suppose, a bucket was used, then electric pumps and washing machines with built-in pumps.

In the old house, we had to put a hose into the bath tub, which would suck water into the washing machine when needed. As is customary, the washing machine was in the room next to the bathroom. This is very sensible architecturally, thermodynamically and ergonomically, but not ideal in our case as the room next to the bathroom was the kitchen.

The new house has a further development, taking the water from the bath directly from the plumbing to a tap in the wall next to the washing machine. This is much easier than a hose to be put into the bath. In our new house, the bath and washing machine are still relatively close to each other, only vertically rather than horizontally: the bathroom, as is customary in England, is upstairs. This still meets the criteria above, keeping all the water pipes in the same part of the house, shortening hot water pipes. We have a laundry shoot so clothes can be sent down from the bathroom to the utility room.

Many people here suggested, or assumed, that it was impossible for the building to take the weight of an upstairs bathroom, but we reminded them that there are plenty of aparment blocks with upstairs bathrooms.

Anyway, we have been having trouble using the bathwater for washing. The flood on the floor when we opened the door was the worst case, but when we did try to use the bath water, the washing machine was using up the entire content of the bath--over 100 litres--in one wash.

In the end, after the plumber coming to fix the tap, which he admitted was a new and untried model, and the washing machine man coming back again, we have heard, once again, that there is nothing they can do. The pump is designed to get bathwater from the same level, not to work as a tap. Because of the height difference and water pressure, once it gets the water going from the bath, the syphon effect will take over and it doesn't stop until all the water has gone. 

The washing machine man shook his head. Nothing can be done. All washing machines are the same. They're not made for upstairs baths. It's impossible to change the pump to one that actually stops water when it's off.

It seems that it would at least be possible to have an electric tap on the wall, activated via a relay when the washing machine switches its pump on, but he didn't seem terrible interested in solving the problem, content to tell us that it couldn't be done. 

Not so Eco and not so cute

The electricity bill for the month of March just came through, and the good news is that we only used 147 kWh. The bad news is that we were away for all of the covered period--23rd February to 25th March--so most of this energy was being used while we were out of the house. Maybe not a big deal in the grand scheme of things. This only added about 1800 yen to our electricity bill, which is little compared to the repayments on the loan, or on the amount they are paying us for our solar electricity generation, which was 45,000 yen for the same period. 

It seems a lot compared to last month when we were in and used 573 kWh. 25% in fact. 29 kWh were used in at-home time, and 117 night time. Only one kWh was used during day time, but this is not surprising as the panels will have been producing electricity for most of this time.

At-home time is 7 am to 9 am and 5 pm to 11 pm; 8 hours per day. For the 32 days, that's a power consumption of around 110 Watts. Night time is 11 pm to 7 am, also 8 hours, and you'd expect the same consumption, but it averaged 460 Watts. The only difference is the eco cute, programmed to come on at night.  Taking 110 Watts as the background consumption of the house, mainly the ventilation system and the fridge, which we left running, but also the circuitry and leds on display panels, and maybe some phantom consumption on the light bulb sensors, that means the eco cute used 88 kWh over the month. That's almost 3kWh per day, and we didn't use any hot water, and the underfloor heating was switched off. The energy it was using was just making up for the heat it was leaking into the house.

I'd set the tank to low temperature while we were away, but when we came back the display said it had one bath and 50 minutes of shower. I suppose this is less than one bath and 90 minutes of shower that it usually has, but this still seems to be a lot of heat. The exact meanings of the high, medium and low temperature settings are far from clear or explicit, and it seems like it's impossible to set them to actual temperatures, for example having the water in the tank at 50 degrees. Also, having thought that I could vary the amount of hot water in the boiler, it suddenly clicked that the setting of full tank, 50 litres or 100 litres is just for the amount of hot water it will add to the tank when you press the re-heat button. It doesn't make any difference to the amount of heat in there.

Without knowing the COP of the heat pump, it's difficult to know exactly how much heat this represents. I can maybe get some ideas by looking back over the temperature each night, and the electricity consumption data, and work out the relationship between the two, assuming that it's losing the same amount of heat each day from the constant set temperature of the tank (whatever that is) to the more or less constant temperature in the boiler room. Heat loss is proportional to temperature difference.

In a way this is the worst possible conditions for heat loss, as the tank was left full. But it was set to the lowest setting, and the boiler is inside. Imagine the usual situation where the boiler is outside, and it is left set to high. 

Eco con

During the explanation session, I asked the plumber about changing the temperature of the boiler, which he said was impossible. In fact, checking the manual and playing with the controls, I found that it was possible. There are three settings for boiler temperature: high, medium and low. Also, there are three settings for the amount of hot water in the boiler: a full tank (460 litres), 100 l or 50 l. 

The plumber didn't actually fit the boiler, so I don't completely blame him (although he shouldn't be telling people things are impossible when he just doesn't know how to do it), but the people who did fit the boiler also put in the underfloor heating, which they switched on to pump hot water through
the whole time, and did not set the boiler to the maximum temperature, so it was both using expensive day time electricity, and running out on us when it came to bath time. So they didn't know how it worked either!

I suspect there are many people, like my parents-in-law for example, who are producing way more hot water than they need and have not been told how to set their boilers properly. The Passive House lady considers this to be a serious national problem, causing massive excess energy use, and a lot of disgruntled customers.

The idea behind the Eco Cute is basically to use cheap night time electricity, from 24-hour nuclear and gas-fired power stations, and not really anything to do with ecology or saving people money. 

People with large households certainly get a good deal with their Eco Cutes, providing they don't run out of hot water. Meanwhile a lot of elderly couples, victimised by silver-tongued salesmen, find that their heating bills go up, on top of the investment of their savings into this new wonder, or worse still having been encouraged to take out a loan to pay for it. Over-dimensioned tanks with insufficient insulation incorrect settings.

The situation in Hokkaido is apparently that so many people are using Eco cutes that there is now a shortage of night time electricity.

Not sure if it's Eco, or cute, but it can certainly do wonders with hot water

The fancy display panel on the wall next to the kitchen allows us to set the tap temperature anywhere between 35 and 60 degrees, and the clever control system will mix the water from the boiler, at a much higher temperature, with cold water to get us what we want.

The bath can be set to fill automatically to a range of heights and temperatures although only up to 48 degrees. So we can't use the bath for making soup.

The system is very intelligent. We tried to fill up the bath with the plug out the other day and very quickly the eco cute realised our mistake and switched off the water.

In our old house about once or twice every week we would either leave the water running so that it was spilling over the top, overheat the bath so that we needed to throw hot water away before we got in, or both.

Little bars on the display panel show us how much hot water is available from the tank. One bar for 50 litres at 50 degrees. 2 bars for 100 l, 3 bars for 150 l, 4 bars for 200 l and 5 bars for 300 l or more. With a 460 l tank, with water over 60 degrees, there will be a full five bars with just half the heat capacity of the tank. I'm having trouble finding in the manual exact temperatures for the high, medium and low temperatures the boiler can be set at, but in the spec at the end, it gives a range of 65 to 90 degrees.

As well as the bars, the display panel will show how much hot water there is, measured in number of baths and minutes of shower. I think it measures a bath as around 30 minutes of shower. At full tank, I've seen it gives one bath and 95 minutes shower, so it doesn't count in multiple baths. That wouldn't make sense in a communal bathing culture, as you can only have one bath.

There's a display panel in the bathroom, but this just shows how many minutes of shower are left. I suppose if you're in the bath, you won't be interested in how many baths there are, as you already have one, and if you're having a shower, you won't want to have a bath. I keep meaning to compare the number of minutes shower on the bathroom panel with the number of baths and minuts shower on the panel down stairs to get a more precise relationship between baths and minutes shower, but haven't managed yet. Anyway it wouldn't be that precise because the number of minutes shower is only to nearest five.

Everything works really well, but it's very difficult to find exact data, for example how hot is the water in the tank? How much is there? How much hot water did we use each day? 

The machine knows a lot of this, and when the temperature is set to "medium", it is looking at how much water we've been using, and heating the water appropriately. Maybe it's just me, but I'd like to know that information too!

Getting into hot water

The heating system was fixed a couple of weeks after we moved in, and we have a panel on the wall under the stairs to adjust it. For all that we're trying to build a house that doesn't need a heating system in a country where houses traditionally don't have them, we seem to have done just that.

I think this is the first house in Japan I've lived in that has plumbed hot water and it's certainly the first house with any kind of central heating system. It's very European in the sense that it effectively has a boiler with a supply of hot water for washing and also for heating. For a day or two our boiler was running out of hot water, but this was because the heat was all being sent under through the pipes under the floor.

Hot water running out is something that anyone who has lived in a boiler culture will be aware of. My wife has never forgotten getting in trouble for using all the hot water when we were staying in a bed and breakfast before my brother's wedding. 

The concept of hot water running out is perhaps alien to Japan. Japanese has a separate word for hot water "o-yu" rather than "mizu", which it is tempting to argue is due to the abundant natural availability of hot water in the country. In many places it simply flows out of the ground. Hot spas spring up in the middle of cities, and clusters of hotels burst out around them in the countryside, in the mountains or by the sea.

Although this is the first house I've lived in with plumbed hot water, every house I've lived in has had running hot water, and copious amounts of hot water available in the bath. The first house I lived in had no running water in the bathroom, but you could fill the bath with water, and then heat and reaheat that. You could heat the bath a little, then you'd get some hot water at the top which you could scoop out for a shower. When she was a kid, my wife used to have to build a wood fire under the bath at her house. So there was a very visible body of water there. 

All the kitchens where I've lived have had a gas geyser that will produce hot water into the sink on demand. Instant hot water that only runs out if the gas is not connected, or if the battery goes in the geyser and the sparks stop working. 

Meanwhile, at around the same time my wife was loading wood to fire her bath a quarter of a century ago in the mid 1980s, I remember on my first stay in Tokyo seeing somebody going to a pay phone and dialling in some numbers without saying anything. He was setting his bath to come on so that it would be ready when he got home. His bath was electronically controlled to supply and heat the water, and the controller was connected to his answer phone, which could take remote instructions.

A tank in the house

Although we put ours inside, we're surrounded by houses with external boilers. As well as conducting heat to the outdoors, they sometimes have long pipes, probably not lagged, taking a while to deliver hot water, and wasting a lot of heat getting the hot water where it needs to go. 

Likely as not, though, they'll be in the traditional position for the bath water heater, right outside the bathroom, which will have a washing machine right next to it so the main water pipes. Unless some wiseguy architect has told them they can put it anywhere they like because the hot water pipes only cost 150 yen per metre. They don't realise that's also what they'll cost in wasted hot water each month.

External boilers are the norm for most of Honshu, the main island, but from the North East and certainly in the northern island, Hokkaido, putting boilers inside is common practice as well as common sense. It should be both in Nagano, which is a particularly cold area of central Japan, a good five degrees colder than the big cities of Tokyo or Nagoya. It seems people here would sooner have a tank in their house than put a boiler inside. 

Electric pipe heaters are also a normal fixture here, winding around outside water pipes, and switching on when the temperature approaches freezing, which can by as many as half the nights in a year up here. More running costs. More electrical devices. More profit for the electrical companies.

One of my concerns, having the boiler inside, is to keep the tank temperature as low as possible in the summer, when our hot water needs will be much less, and the heat leaking from the boiler is going to be making the house hotter.

Taps

The first time one of the kids went to wash his hands, it sounded like he was using a shower. It's not really the kid's fault for turning it on full volume, but why does full volume have to be like a shower? It's only a sink for washing hands and faces and cleaning teeth, I thought.

However, closer inspection reveals that you can pull the head of the tap out and wash your hair with it. So in fact it is a shower. Even so, it's not a shower most of the time.

When taps used to be wheels that would turn to open, it was more obvious how much flow you were going to get. If you wanted a lot, you had to turn the tap a few times.

Once they started with these new-fangled lever-taps, the electronic generation just thinks of them as switches. On or off. Either nothing or full force, unless you want to be really careful.

So I realised that what they should do is make taps more like bicycle brakes. The more you want the water to come on, the harder you have to twist. At the moment it's the opposite. You have to twist hard to get any water at all, and then there's very little difference in the twisting strength you have to apply between the thinnest trickle and a full torrent. I don't mean you should have to twist really hard to get full volume; just harder than you have to twist to get a trickle.

This is what you'd get if it was an iPhone app.