Jeremy Harris

Needs to be screened, insulated etc, hence the suggestion that Konex was probably the only reasonably choice, other than doing away with the data cable and running data over power.

Pretty good summary. The conical single tank systems have an advantage that the air flow blows the sediment up from the bottom and recirculates it so that it has multiple passes through the high oxygenation zone. This tends to reduce the volume of sludge, by aerobic digestion into liquid effluent for some of it.

There's a big difference between a septic tank, that was designed to run as it's name implies, as an anaerobic septic (and hence toxic) settling tank, that did nothing more than break down solids, and a treatment plant, that is designed to significantly reduce the level of organic sludge (by aerobic digestion) and run in aerobic mode, which means that it's essentially non-septic, clean-smelling and produces fairly clear effluent that has a low BOD. To some extent there was an "out of sight, out of mind" approach to effluent disposal, and few worried about leach fields that had stopped working or any pollution they were creating, as long as they couldn't see it.

What is it you EXACTLY want to be warned about? Sensitive leak detection at the one drip every few seconds level is near-impossible on the water feed side, as you need to be able to differentiate between legitimate slow water use (like the final stage of a cistern fill cycle, where the flow rate may well be tiny, or someone leaving a tap dripping) and genuine leakage, which may well be of the same order of magnitude. It's possible, but means having loads of sensitive flow sensors on every pipe and then subtracting the legitimate flow from the total flow to get the leakage flow. On the other hand, if you just want a warning of a slow leak that could cause damage if it's not checked, then just put a tray underneath the probable leakage point, as a bund, fit a simple water detector and let the output from that trigger an alarm/water shut off. Out in our treatment plant shed, I fitted a 2 x 1 upstand all around the perimeter of the 22mm OSB floor, sealed the whole floor with several coats of the sealant stuff used for tanking behind showers and then just fitted one of those WS-1 sensors, screwed to the wall so that the sensor is almost touching the floor (it has two moulded in plastic stand offs to space the sensing conductors just clear of the floor). That's wired to a 12 V supply and a beeper, so if one of the pressure vessels or any of the pipework in there develops a leak, the beeper sounds. I could pretty easily wire the alarm to the pump power, to cut it off in the event of a leak. As a back up, I glued in an overflow drain so that if the water level on the floor exceeds about 1/2" the water just runs to a visible outside drain via a pipe. I'm planning to do exactly the same where the water softener sits and where the internal 100 litre pressure vessel sits, but with both of those I'm just going to use a suitably sized plastic tray as the bund.

A friend of mine is a dietician and nurse, and she is becoming increasingly convinced that many, many more people are sensitive to their diet than was the case years ago (she's around my age, recently retired, but still doing voluntary work). Although there is clearly a great deal of BS around, just as there always has been, there seems to be a growing body of properly conducted, peer-reviewed, studies that are associating diet and health to a far close degree than we had assumed in the past. The really big problem is that there are orders of magnitude more pseudo-science and total BS around, especially on the internet, so it's quite challenging to sift out truth from fiction.

On the topic of wheat, and as a farmer's son, I have to say that modern farming methods do cause me concern. For example, I remember when we were first sold Round Up (glyphosate) back in the 70's. The reps demonstrated it's safety by drinking the stuff, believe it or not. Lots of trials showed that, when used as intended, to kill spring growth of weed prior to seeding, or for weed suppression around field boundaries (not something we'd really do now!) it was very safe indeed. I must have sprayed tens of thousands of litres of the stuff, and genuinely believed it was as safe a herbicide as you could get, based largely on the large body of evidence that proved that soil bacteria break glyphosate down within a few days, so there were no toxic residuals. However, we now have the situation where glyphosate is used to reduce energy bills, by being sprayed on crops before harvest in order to dry the seeds, by killing off the plants. This saves a great deal of energy in wet summers, by not needing to run grain driers as much. The major downside is that if the glyphosate is not washed off the crop, then it will be on the grain or seed, so gets into the food chain. I'm now far from convinced that this is a safe practice, as there seem to be low levels of glyphosate in a lot of grain and seed based foods, and none of the initial safety studies looked at the scenario of long term continuous low level ingestion - they all assumed that there would be no residual glyphosate in the crop come harvest time.

With the benefit of the experience of removing one that had been in place for around 30 years or so, I'd say that might work. The fibre washer is the problem, as it will be bonded on well to both the immersion heater and tank flanges. They always seems to tear when you remove an immersion, so anything that makes it easier for the washer to tear and so allow the immersion to unscrew more easily seems to make sense.

Aeration doesn't need a lot of air at all to be effective. It's hard to get hard facts, as it seems pretty much all the treatment plant designs around were designed empirically. The designers just thought something up, built it, tested it, then tweaked it a bit to make sure it passed the testing under EN 12566-3. In every one I've looked at, assuming some figures for the biological oxygen demand (BOD) of the incoming effluent and then looking at the efficiency of getting oxygen into it (not air - there's a difference, as solubility varies a great deal with bubble size and temperature) it seems that all the pumps I've seen are massively over-sized for the actual oxygen requirement. That's safe, in that too much oxygen eliminates all possibility of the tank becoming anaerobic (a bad thing, as it will tend to kill the aerobic bacteria that do what we want in terms of treatment), but it's both wasteful of power and runs the risk that the start up time after a period of low utilisation might be too long, risking effluent with a higher BOD than allowed being discharged until such time as the aerobic bacteria have multiplied up to the right level again. I reckon that it is perfectly possible, with the efficiency of easily available pumps, to get the electrical power demand to below 15 W for a typical 4 person unit. That's roughly equivalent to around 7 or 8 watts of actual air pumping power, something even a very small wind driven air pump could deliver. The key is finding a way to reliably measure the BOD in the effluent discharge section of the tank and then using that to control the aeration process. If that can be cracked then the benefits are significant; a responsive system that will tend to maintain the aerobic bacterial colony at around the optimum level all the time, a more consistent effluent discharge quality and a much reduced power demand. My target is to convert our system so that a single standard size solar panel on the roof of the small stone pump housing I've built will be more than enough to run the treatment plant and it's alarm system all year around.

Is this where we start the sweepstake on whether or not the old immersion comes out at all?............................. I will freely admit that I struggled for hours to replace an old one once, it was well and truly stuck tight. That was in a house in Cornwall, too.

I believe there are reed bed systems around that need little more than regularly trimming back the reeds, now. We looked at fitting a vertical reed bed system, but couldn't quite get it into the space available, and, IIRC, the maintenance was too onerous. Discharge to the watercourse will be a doddle if you use an approved treatment plant. Although the EA messed us about with flood risk assessments and adding clauses to our planning permission to make sure that no mud or rain run off from our site reached the adjacent stream, they approved my application to discharge the treatment plant into the stream within a few minutes! This may rule out a reed bed, as you may find that you have to argue with the EA as to whether it provides good enough tertiary treatment. All the evidence suggests that reed beds are far better than treatment plants at doing this, but that doesn't wash with the bureaucrats at the EA, who would rather see a certificate than proper evidence................ We're on clay, too, so a discharge to the stream was our only option. Whatever treatment plant you go for, look carefully at the location where you are planning to put it and how easy it's going to be to access it. They generally need de-sludging once every two or three years and some of the unpowered ones need a vertical differential between the vents, to get enough natural aeration through whatever media they use. Look carefully at the internal mechanical design of any non-electrical design, too, as the media does need replacing periodically and the arrangement to fitting it in some units makes access a bit awkward (and messy). Most use something like coir as the aerated media, perhaps on some sort of rocking tray arrangement, so that it gets regularly tipped over towards the fresh air vent. All of the unpowered units use natural convention to pull enough air over the media, hence the need for the exhaust vent to work as a chimney. Sadly there is some pretty poor engineering in some of these units. One I looked at, as a cutaway at the Swindon self build place, had an electric motor, shafts, bearings and a toothed drive belt inside the tank. I hate to think what a job fixing any of that stuff would be.

Shouldn't need PTFE tape. It will either seal with a fibre washer or an O ring and both seal on the flange, not the thread. Usually there's no need to put anything on the thread, but I know from experience that some old school plumbers put boss white on everything as a matter of course. hence my earlier comment about that helping to get the damned things stuck in place.............

I've always found that a bit of diesel works pretty well, better than WD 40, but pretty much anything that will penetrate and help to unstick the thing will help. Older immersions had a fibre gasket as a seal and that seems to be most of the problem, rather than the threads. The last immersion I fitted had an O ring, and was fitted with a smear of silicone grease, so I'd guess these newer ones are a lot easier to remove. I buckled the top of the cylinder the last time I removed one, luckily without doing any serious damage, but that was after copious applications of penetrating oil etc. The problem there was that the fibre gasket had stuck tight to both sides, so when it did come apart it was because the gasket just tore itself apart. IIRC, the threads weren't stuck at all, it was really just the fibre gasket that was the main problem.

It's a damaged 50mm duct (see other post), so this may be tricky, even over 20m. I guess it depends on the run and how damaged the duct is where it's been repaired. One thought I had was to run a bit of armoured duct in there for the data cables, but looking around I couldn't find anything that seemed to fit the bill - standard galvanised steel armoured flexible duct, earthed at either end would probably corrode eventually, I think, as there's water in there now, apparently. I'm not sure how good it would be at screening, either, as it's not designed to be used like this AFAIK. Edited to add: Just had a look at the spec for Kopex FLB. It looks like it "might" do the job, as it has a non-conductive outer that is watertight. Run the data cables in this and the SWA down the duct and it "might" work OK. It's just barely compliant with the regs, though, as it's arguable as to whether the Kopex is, strictly speaking, non-conductive. I'd argue that the outer plastic sheath makes it so, so the only issue is making sure that the end terminations are well separated, as they aren't insulated. Kopex FLB isn't cheap though. I haven't bought any of the stuff for ages, but do remember the wallet-shock the last time I needed a length to wire up a machine tool. Edited again to add: I've been looking around and there is a cheaper alternative to Kopex on Ebay: https://www.ebay.co.uk/itm/20mm-Flexible-Steel-Conduit-Kopex-Waterproof-Underground-Cable-Duct-IP54-Per-M/122191835331?epid=526357490&hash=item1c733370c3:g:-3kAAOSwk5FUsUeg You'll need end fittings as well, and you'll also need to check to see if he can supply the length you need as a continuous run - some suppliers can only do relatively short lengths in one run, as this stuff is mainly used in industrial plant rooms and the like. If you think you can get the data cable(s) down a 12.5mm bore, then you could also look at going down to the 16mm Kopex FLB: https://www.superlecdirect.com/p-flb0330-kopex-16mm-liquid-tight-pvc-flexible-conduit-kopex/

What puzzles me is why we are seemingly getting more people suffering with allergies. Apart from hay fever and a few well-known serious allergies, like those to nuts, it seemed pretty rare to come across people that were allergic to things years ago. Now it seems to be a pretty common problem, with far more people suffering from them. Over the past ten years or so I've developed an allergy to something that only seems to be around during cool, damp, weather. I've resisted going for patch tests, because by a process of elimination I've concluded that it's probably a mould spore of some kind, perhaps one associated with trees, as the symptoms are definitely worse after a walk in woodland in autumn or spring. It's not a major problem, but does mean relying on antihistamines if I want to be able to breathe properly and not have constantly running eyes when the spores are about. I can't help but wonder at what the underlying cause is for the seemingly large increase in conditions involving our immune system misbehaving. I have a suspicion that being too clean, and ensuring clinical levels of cleanliness in our homes, may be a contributory factor. Perhaps we all need constant, low level exposure to dirt and stuff in order to keep our immune systems functioning properly. I do know that it's damned annoying once you do acquire an allergic reaction to something - right now I'm typing this up under the influence of antihistamines, as last night seemed to be pretty bad for some reason. The symptoms go away in the new house, almost certainly because of the MVHR I think, so I'm hopeful that I'll end up less dependent on medication when we finally sell this house and move to the new one permanently.

With Newark, they will fit the holes wherever you want them, as they are made to order.

About £350 inc VAT, plus carriage, from Newark: https://shop.newarkcoppercylinder.co.uk/vented-copper-cylinders/direct-economy-7-cylinders/1500x450-direct-e7-copper-cylinder Might be a struggle to fit a newer cylinder, as the extra insulation may make it a tight fit.

Copper should be OK, as with water that is slightly acidic, and hence a good electrolyte, you don't want a different metal if you can avoid it. A 14" element should fit fine in an 18" cylinder, I'd have thought, but if you're at all concerned there would be no significant performance difference from fitting an 11" one. Any reputable supplier should be OK, as these things seem to be pretty generic. Your challenge is going to be getting the old one out - they can be really tough to remove when they've been in for a few years, and being a 30 year old one I bet it's been fitted with hemp and boss white, which won't help.

Interesting. I'll point a CCTV camera at mine to see if I can see anything. There's no visible light, but if they're using short wavelength IR LEDs then they should show on any CCTV with a night vision capability. As it happens, I park facing one of the cameras, so I'll take a look and sew if there's any IR with the ignition on. I'd assumed they were capacitive based on observations of the electrode pattern on the first car I had with this system, years ago now. There seemed to be rows of interlocking "fingers" sputtered on to the inner face of the glass, so my guess was that they were just looking for a change in the dielectric constant, in the same way as external electrode level sensors work. I made level sensors for paramotor fuel tanks for a few years, as kits, and these used a capacitive sensor with the fuel as the dielectric. They worked pretty well, and were a lot easier that tryign to crane your neck around to look at a mirror pointing at a translucent fuel tank.

Yes the Foxx system is a modular system that allows interconnectivity between sensors. There are a range of Foxx modules available, I believe. Seems a complex way to make a simple water level alarm though, when all that's needed is a cheap and reliable sensor and a beeper or LED (or both) , really.

This isn't really on, as mentioned in the other post. The minimum separation is 300mm between power and data cables, but in practice you can get away with a bit less, say 200mm, without getting interference over short runs like this, although it's not recommended. For safety reasons as much as anything else you shouldn't put power and data in the same duct, even if there isn't an interference problem in practice. The only exception I know to this rule is for pure fibre optic data "cable" with no electrical conductors. I believe it's OK to run that alongside power cable OK.

I think the car sensors are capacitive- there are no conductors on the outer surface of the glass that I can see, and I think they work by the change in dielectric constant when rain drops bridge the internal electrodes under de the black layer inside the glass. They probably have low level AC across them and get loaded down when a water droplet is on the outer face of the glass. I could be wrong, but that's how I guessed they worked when I first looked at one. Those WS-1 sensors I linked to earlier are so cheap and easy to use that it's not really worth mucking around with home made solutions, IMHO. £4 and it will switch up to half an amp directly for an alarm, it's potted in a sealed box and has gold plated contacts that won't corrode. When I tried to make a beeper wire for measuring the RWL in our borehole I found that one problem was that you need a material between the sense wires that doesn't retain water - it must be strongly hydrophobic - otherwise the beeper keeps going when the thing is out of the water, from the water film bridging the electrodes. The plastic that these WS1 sensors are made from doesn't allow a water film to stay put, so gets around that problem.

There should be at least 300mm, preferably 400mm, of separation between the SWA and the data cable duct in the trench - they must not run in the same duct. The SWA does not need to run in a duct - it's just easier to do so a lot of the time, as it makes replacement easier. It's OK to run a low voltage DC power cable down the duct alongside the data cable, if that's any help.

Welcome, There used to be a solar power option for the unit we have, the Bio Pure, that they only stopped producing because the batteries and solar panels were vulnerable to theft (or that's what they told me at the time). This means that it is possible to use the very good blower aeration technology without mains power. It might be worth ringing Bio Pure (they are only a small company) as asking if they can till supply the solar system, if you think that in your location theft might not be a significant risk. I've had an in-depth look at the amount of power an aeration system really needs and it is a LOT lower than that used by the majority of the pump systems that these companies use. The bottom line is that the aerated treatment plant companies are using pumps that are designed and manufactured for aerating large fish ponds (most are made for Koi carp ponds) and just re-purposing them. The fact that they massively over-aerate a treatment plant is only really being addressed by one or two companies, and even then they only use pretty crude timers to reduce the amount of time a standard fish pond pump is on. There is definitely scope for a system that measures the biological oxygen demand (BOD) in the final discharge chamber and then intelligently adjust the aeration level to maintain that. This would allow for periods when the house is not occupied as well as periods when there are guests staying, all the time maintaining exactly the right amount of aeration to avoid the need for tertiary treatment. Sadly I know of no company that makes such a system, but AFAICS it would not be hard to do. One of my long-term projects is to add some form of BOD measurement sensor to the effluent chamber on our system and see if I can come up with a way to run the air pump more intelligently. Although pumped aeration is far an away the best system, because is both aerates and stirs up settling sediments for digestion, passive systems can be made to work, although some have had mixed reviews. One system that works extremely well if you have the space, is a settlement tank followed by a reed bed treatment system. Reeds are exceptionally good at providing the aerobic final treatment stage, as well as removing pretty much all the nitrates etc, so will usually give a very clean discharge. The down side is that the settlement tank (nothing more than a conventional septic tank, really) will probably need emptying more often than with a pumped air system, as there is no mechanism to circulate and digest sediment. There are some really quite poor designs around, but the key thing is that to work well the main treatment stage must have adequate aeration, and this aeration depends on the usage. Conventional septic tanks relied on aeration from the land drains and aerobic soil bacteria, but this is inherently poor, as within 10 years those land drains will have grown biofilms and have become anaerobic and septic. The easy check for this is to dig next to one and check the soil colour. If it's turned grey or black then it's septic and no longer treating the effluent, whatever drains away will have a high pathogen count and a high BOD, without a doubt. Both are bad news for watercourses nearby, as well as livestock and wildlife.

Pretty sure this was the disaster that ended up on TV a few years ago. Really bad design flaws, like toilets that you couldn't get into because the door hit the pan, daft plywood "chimneys" that were supposed to work as passive ventilators, but didn't and a whole host of conflicts between the design team and the builders. I'm pretty sure they didn't meet half the targets they'd set, either.

Mine too. I use these fairly cheap and easy to use sensors, that have gold plated electrodes so tend to give better long-term reliability: https://www.rapidonline.com/Electronic-Components/Liquid-sensor-66470 They are easy to wire directly to a small alarm beeper, like this: https://www.rapidonline.com/rvfm-12v-low-profile-buzzer-35-0041 and a suitable power supply to make a very effective alarm.