Urinals seems sensible when you're in a public loo, so why haven't they caught on in UK bathrooms? They don't take up much space or plumbing. Ben Miller, Edinburgh

Well, thank you for that tremendous response to an admittedly leftfield question. The answers you collectively gave ranged from the sublimely ridiculous through to the genuinely instructive.

There seemed to be universal agreement that using up to a dozen litres of drinking water to flush away a bit of pee is excessive, but not everyone agreed that urinals in the home make for such a great alternative. Valid questions about hygiene, lack of space and "gender applicability" were prominent in the discussion. McMuggins spoke as only a male could when he said (I'm assuming it's a "he") to "Go tippy toe and try a sink". That may well be the solution if you live alone, but I can't see co-habitants of any home welcoming it as a long-term alternative to the urinal.

I'm also not too convinced by SE14bloke's idea: "Combining early-morning slash with a shower saves one flush per day (and that is a truly unisex technique... )" We don't have too many, I know, but we do have some standards here at EnvironmentGuardian. I'm not going to endorse peeing in the sink or the shower as practical 21st-century solutions to cutting back on water use in the home.

Teratornis came up with the standard response of a "good lifer": "Pee in a jug and pour it on your compost pile. The nitrogen and phosphorus content will nourish the bacteria that break down tough lignocellulosic yard waste faster. Urine diluted with five parts water also makes a great fertilizer applied directly to plants." But, again, this is clearly not to everyone's taste.

I very much liked the water-saving solution offered by itakitez. The "WS7716" toilet, which uses only three litres per flush, promises annual savings of 79,000 litres, assuming "5.1 flushes per day per 1.31 persons using each toilet". This from the Watersave website:

"This toilet uses pressurized air to create a powerful vortex and vacuum effect, creating a flush unlike any on the market. There is no need for a dual-flush when an HET (high efficient toilet) is installed, and the patented Niagara flush system will clear the bowl any time, eliminating double-flushing."

Sounds great. I love a loo with a "Niagara flush system". The only problem is the price: €190 (£168). A much cheaper water-saving device that looks like a good bet is the InterFlush, as mentioned by neroS: the kit costs just £15 and adapts the handle into one that stops the flush as soon as you release it, meaning you only use as much water as is required to "clear the pan". Why don't they just make this standard for all loos?

Waterwise, the UK NGO that is "focused on decreasing water consumption in the UK and building the evidence base for large-scale water efficiency", also has a wide range of water-saving gadgets and gizmos listed on its website, all of which have been awarded the "Waterwise Marque".

But my favourite comment was provided by Davollsdavoll:

Grey water is a really good start. If we use the bath at home, we keep the water for flushing the loo until the bath is needed again. (Living on the first floor and having no garden, we can't have a water butt.) I'd like to see plumbing 2.0, where we either have an option on every sink/plughole to either bin the water or to "grey" it (something more catchy would be better probably). So much goes down the plughole, it's criminal!

I love the idea of plumbing 2.0. You're right, of course: using grey water to flush our loos makes complete sense. It's a genuine mystery why homebuilders are not made to install grey-water systems in new builds as standard.

As things presently stand, our loos in the UK must match up to the Water Supply (Water Fittings) Regulations 1999, which states that, ever since a "performance specification" was introduced in 2001, WC suites must deliver "a single flush of six litres maximum or a dual-flush of six litres maximum and reduced flush of no greater than two-thirds of the maximum flush".

How long must we wait for this "performance specification" to be tightened to reflect the fact that much of the water we wash down our plugholes could be retained and used to flush our loos?

On 29 March, Leo Hickman first wrote:

Using up to a dozen litres of fresh drinking water to flush away your "business" does seem somewhat excessive, and there have been various attempts over the years to get us to use "hippos", bricks and the like to decrease the amount of water we waste when pulling the chain.

But, as far as I'm aware, the use of urinals has never taken off in the home. There are some good reasons: they're not exactly unisex devices, despite the best efforts of some women, and I can imagine the wandering hand of a child coming to grief on the porcelain lip.

Do they use less water, though? There are some "waterless" urinals around, plus ones that are motion-activated. But would you really ever consider installing one at home? Post your thoughts below and I'll be back on Friday to round up the best comments and provide an in-depth answer.