It started with some simple data collecting after I moved into my current house. After realizing the amount of rain that was being wasted (mainly under my house) I had to act. I sketched a few rudimentary ideas on a napkin at work but soon became distracted by life (a few kids, leveling the house, adding gutter diverters away from the house, etc.)
The drive to design and build an efficient rain collections system resurfaced a few months ago and this time I wouldn't let go. So follows is my rendition of rain harvesting:
Step 1: Ingredients
3. Water Tank (NTO tanks has several selections at a reasonable price with surprisingly quick service)
4. First flush system (After designing my own I found Rain Harvest Systems with an almost identical system)
5. Numerous schedule 40 PVC pipes/fittings (see pictures)
6. Just see pictures for the other stuff.
7. Basic tools (i.e. saws, glue, tape, markers screw drivers, outdoor screws, drills, etc.)
Step 2: First Flush
The idea behind a first flush is to separate the general gunk that comes off your roof, that most gutter systems miss, from your collection tank. The amount to divert to the first flush depends on the size and contamination of your roof. For my test roof : Approximately 700 sp. ft; a 18 gallon first flush is more than adequate (see the website for resources)
The company Rain Harvest Systems has a complete kit (actually multiple kits... I really wish I had found this company earlier in my designing and building)
Follow their instructions or use their designs as inspiration to build your own first flush system. In the end it doesn't matter which you do. The length of 3" or 4" pipe required for an sufficient flush would take up more space and would be close in price to a three foot section of 12" pipe added to this company's 12" to 3" reducer. This was a case of "They got it figured out with a product at a reasonable price. Guess I should buy it."
Step 3: Floating Intake Filter and Outlet
The bottom bulkhead for my tank was 2". So everything bought was to attach to this piece and then size down to a garden hose connection on the outlet end (separated by a gate valve) and a 5/8 ID hose on the floating filter end
Fairly straight forward construction here:
Take your 2" threaded bushing and attach 2" to 3/4" bushing
Attach your chosen gate valve to your brass couplings with plumber's tape
Attach to 2" bulkhead using plumber's tape
Admire and eat pizza as celebration
Be gluten intolerant
Go to Museum of Tolerance
Floating Intake Filter:
Assemble another 2" threaded bushing with 2" to 3/4" bushing
Attach Brass adapter (5/8" to 3/4" threaded) to hose, tighten #012 ss clamp
Attach Nylon adapter (1/2" to 3/4" threaded) to hose, tighten #012 ss clamp
Attach 1/4" eye bolt to toilet tank float and attach to Nylon adapter end of hose (number of methods to accomplish this: 1- With fish line and about 6" of slack or 2- Place nylon barb through eye bolt prior to attaching hose)
Attach water bubbler to nylon end
Attach brass end to already assembled 2" threads
Lay tank on its side and attach to 2" bulkhead with plumber's tape
The idea behind the floating filter is to have it float a few inches below the surface (to avoid any floating contaminates) and to collect water above the bottom of the tank (to avoid sediment). If you're worried your tank will run dry then attaching some fish line to your float and the top of the tank would at least avoid sucking up the sediment. There are commercially available floating extractors/filters but the price is quite steep. (ex. Rain Harvesting Supplies) So spending $30-$40 is much cheaper.
Step 4: Overflow
The overflow is also straightforward. Just attach a P-trap to a length of 1 1/2" pipe (This is variable based on your tanks design. I had to extend past the taper of my tank to allow it's required height) then attach that to a 1 1/2" threaded bushing which then attaches to the tanks 1 1/2" bulkhead with plumber's tape.
Some thought did go into this basic design:
A P-trap is meant to keep In---In and Out---Out.
At the end of the P-trap attach a short section of 1 1/2" pipe cut at an angle (This allows any floating junk to siphon through the overflow and further increases the quality of your collected water)
The angled piece also raises the height to above the discharge end of the overflow so that gravity can do what it do.
The drain cap... I haven't yet determined how much use it serves at this time so I haven't installed it. Because I could only find a 2" drain and not an 1 1/2" drain, I would have to attach a 2" to 1 1/2" reducer to even use it. This seems a bit superfluous as I already have the P-trap in place.
Step 5: Final Attachments
The location of the tank was logically placed close to the test roof's gutter downspout (Why spend extra money on long sections of pipes?). As an added level of convenience for this location, there were several already level concrete stones here. For a tank with these dimensions 16- 1'x1' blocks provided a good footing. You will have to use your own discretion on this part... actually you're going to need to use your own discretion on all the remaining steps. This is not an exact science.
Put it close and level to your downspouts (use concrete blocks, pour a pad, whatever you got)
Attach the 3" T-piece (Since my Leaf Eater was located at the end of the downspout and the first flush below this I had to play with the required lengths of 3" pipe between connections. Ultimately make the final connection to the leaf eater and screw it in it's final location below the downspout.)
Rough fit all the remainder pieces to fine tune the length of pipes and rotation of the fittings
I settled with a 2' section of 3" pipe at a slight decline from the 3" T-piece (supported with a #072 ss clamp), a 3" elbow/90 attached parallel with the wall
Use the two 3" rubber couplings to fine tune the rotation of the 3" elbow/45 to locate the position for the bulkhead installation on the tank
Use the rough in detailed above to locate and mark the placement.
Remove rough in and screw hole with 3 1/4" hole saw
Clean edges and attach bulkhead with rubber gasket on inside of tank.
Attach 2" threaded bushing to bulkhead
Attach 3" to 2" reducer to bushing
Attach 2" threaded bushing to bulkhead with short length of 2" pipe
Attach 2" elbow/45 to length of 2" pipe (this varies based on height of tank)
Attach 2" elbow/90 to 2" elbow/45 to end of 2" pipe
Finally attach diverter to the short 2" pipe inside tank
(The idea behind the diffuser is to avoid disturbing the sediment in the bottom of the tank)
Using the two 3" rubber couplings attach the 3" elbow/45 with short section of 3" pipe to the tank and to the downspout
How to construct this last bit:
During the rough in detailed above you end up eyeballing the approx. length of each section
Then attach the piece making sure that the elbows are still going to line up
Then once these pieces are to the length they need to be
Cut them in half and use the 3" rubber couplings to attach everything.
(The idea of course to allow for easy assembly, disassembly, and maintenance)
Step 6: Final Thoughts, Etc.
I believe this build went surprisingly well, considering I have no plumbing experience. Total time to build once supplies were in hand: Two days (that's 4 hours [There's a two hour window where both children are napping and their bellies are full]) It almost took 2 hours in Home Depot just finding all the parts. This part will go much faster with the next tank. I am now just waiting on it to rain so I can fully test my system.
Total cost: ~$930
Tank: $438 (www.ntotank.com) [includes shipping]
First Flush: $262.61 (www.rainharvesting.com) [includes shipping]
Fittings: $209.01 (Home Depot / Lowes)
Filters: $38.86 (Amazon / Lowes) [Actually bought 4 bubblers, so closer to $6 without shipping]
Additional Fittings/etc: 15 [To correct the little flub of getting the wrong connection size]
Additional reading is attached (again... wish I found this before I invested so much time in my design. Could've just borrowed everything from the different resources)