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using rainwater in toilet cisterns

  • 15-04-2014 8:48pm
    #1
    slipstream
    Registered Users Posts: 198 ✭✭


    the architect on our bungalow renovation has suggested using gravity fed filtered rainwater from the ~ 25sqm flat dormer roof for the toilet cisterns.

    to do this, i guess we would need a separate cold water storage tank, rainwater header tank with overflow and perhaps a mechanical mains top up valve.

    we would hope to connect toilet cisterns and perhaps the washing machine (if it was advisable) to this.

    do you guys have any experience or advice on setting this up?

    slip


Comments

  • #2
    Pocoyo
    Banned (with Prison Access) Posts: 1,587 ✭✭✭Pocoyo


    Yeah its totally fine and if you live in a hard water area its all the better for your washing machine. Good idea ''give that man a can of coke''


  • #3
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    Done this
    Separate header tank fed by pump from rain water to top of tank controlled by standard ball valve
    1/3 of the way up the second fed with is mains but controlled by solenoid valve with float switch so you never run out if water
    Mains is back up but low water content in that tank works a treat


  • #4
    slipstream
    Registered Users Posts: 198 ✭✭slipstream


    richieburke01 wrote: »
    Done this

    good to hear i'm not the first!
    richieburke01 wrote: »
    Separate header tank fed by pump from rain water to top of tank controlled by standard ball valve

    what type of filters did you use? do these require much maintenance?
    richieburke01 wrote: »
    1/3 of the way up the second fed with is mains but controlled by solenoid valve with float switch so you never run out if water
    Mains is back up but low water content in that tank works a treat

    do you think an electrical or mechanical mains top up valve would be a better idea? where did you get your setup or did you build it yourself?

    slip


  • #5
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    Solenoid valve is standard 1/2" but normally closed with power off and float switch to talk to valve when mains water rising in the tank
    Set the float as low as possible just as back up :)


  • #6
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    Sorry any decent filter will do
    Maybe charcoal might be best


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  • #7
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    richieburke01 wrote: »
    Solenoid valve is standard 1/2" but normally closed with power off and float switch to talk to valve when mains water rising in the tank
    Set the float as low as possible just as back up :)
    richieburke01 wrote: »
    Sorry any decent filter will do
    Maybe charcoal might be best

    where did you aquire these items? how much?

    I thought I read somewhere here you needed a multistage filter?

    I've been thinking of doing the same and have been wondering how to control it.
    Do you have any pictures, I see you're saying you have two feeds, one from your rainwater supply and one from mains in case the rain water is not enough to feed tank.

    How do you have the pump coming on when the ball valve opens for the rainwater? is it a negative head pump you're using so sensor detects low pressure and turns on?

    Was thinking of pumping from water butt up to a seperate header tank with the plan of supplying, toilets and potentially washing machine, using a Lidl pump to try it out, other pumps would probably be more expensive to start with, but it would mean wiring some kind of circuit from the tank sensor to the pump.

    Any ideas on allowing bath/shower run off be collected and maybe mixed into the rain run off for use, I plugged the bath once to see how much water the electric shower used and despite not taking long in there, it was 1/4 way up the bath, enough to fill a few cisterns.


  • #8
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    South Coast valves in cork
    I'm only feeding toilet nothing else you would need serious filters to put it to domestic water


  • #9
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    Negative pump in an old well we found on site
    Builder put all rainwater into this well 30 feet deep
    We dropped pump in
    Pump it up to header tank and gravity takes over to toilets


  • #10
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    richieburke01 wrote: »
    South Coast valves in cork
    I'm only feeding toilet nothing else you would need serious filters to put it to domestic water

    Initially, Id intend to only supply toilets also, it will probably be a long time before I get round to it.
    Maybe washing machine, but not for drinking.


  • #11
    richieburke01
    Closed Accounts Posts: 217 ✭✭richieburke01


    Very good
    Cost about €300 all in including pump and header tank and valve


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  • #12
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    Anyone know a supplier of these kind of items in Dublin? filter and fiter bowls and the like.
    I've seen filters and bowls in B&Q, but apart from seeming pricey, they dont seem like they would be as hard wearing as a good quality item/as likely to be able to source spares for replacement or consumable items like filters at a good price/quality/in bulk.
    I was looking for something that acts as a switch but can be fitted directly to a tank, say like a float valve but which has an electrical connection (12v?), and possibly also capacitance sensors for low level.
    rather than the float switch which looks like its bunged over the top of the tank.


  • #13
    slipstream
    Registered Users Posts: 198 ✭✭slipstream


    i've looked into this a little further.

    here is a list of the outstanding queries/issues i have -
    1) What type of filters to use?
    do these need to be replaced?
    do they require maintenance? if so, how much maintenance is needed?
    2) Would inlet/outlet pipes to/from the tank be insulated to reduce cold bridging (more of a construction than a plumbing concern)?
    3) Would a water trap be needed on the inlet and outlet (to aid air tightness amongst other things)?
    4) Where would the overflow go if the rainwater storage tank is full?
    5) Would a mechanical or electrical mains backup for when the tank is empty be better?
    6) I have heard concerns that a basic system could fill with bacteria (even moreso in a warm roof). What are peoples thoughts on this?
    7) Would the rainwater would be suitable for use in washing machines?

    thanks for your advice,

    slip


  • #14
    murphaph
    Registered Users Posts: 19,018 ✭✭✭✭murphaph


    Filtered rainwater is likely better for washing machines, especially if you live in a hard water area.


  • #15
    cerastes
    Closed Accounts Posts: 3,601 ✭✭✭cerastes


    slipstream wrote: »
    i've looked into this a little further.

    here is a list of the outstanding queries/issues i have -
    1) What type of filters to use?
    do these need to be replaced?
    do they require maintenance? if so, how much maintenance is needed?
    2) Would inlet/outlet pipes to/from the tank be insulated to reduce cold bridging (more of a construction than a plumbing concern)?
    3) Would a water trap be needed on the inlet and outlet (to aid air tightness amongst other things)?
    4) Where would the overflow go if the rainwater storage tank is full?
    5) Would a mechanical or electrical mains backup for when the tank is empty be better?
    6) I have heard concerns that a basic system could fill with bacteria (even moreso in a warm roof). What are peoples thoughts on this?
    7) Would the rainwater would be suitable for use in washing machines?

    thanks for your advice,

    slip

    Filters would have to be changed periodically, I used to be in a job that used filters that looked similar in material and size to whats available in B&Q but for a different liquid chemical.

    Id have thought a venturi connected to an inverted bleach bottle inline just prior to the storage tank for the collected water could suck in an appropriate small amount of bleach that would mix and aid keeping the water clean and bacteria free, if it was already strained and filtered.


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