drinking water network and an agricultural water network

[Bili]

We have a drinking water network and an agricultural water network. The agricultural water network is connected and receives water from the drinking water network. What separates the agricultural network from the drinking water network is a backflow preventer, so that water can only pass from the drinking water network to the agricultural water network but cannot return back from the agricultural network to the drinking water network. The goal is to prevent the agricultural water network from contaminating the drinking water.
Currently, the agricultural water network is in a separate water line layer.
The question is how to implement this in the UN network, is it better to implement it as a separate water network, or as a DMA network

[AyanPalit]

@Bili Interesting topic and multiple modeling options depending on your use case.

One way to look at this: you have a single product 'water' in the network. This typically drives the choice of 'domain network'.

The partitioning of drinking water network and an agricultural water network can be achieved through one of the many techniques discussed here: 

 Utility Network Architecture 

I would recommend a singular utility network, given the product (water) does flow from the drinking water network to the agricultural water network. A single utility network will also streamline data maintenance and reduce system overhead. But do consider use cases specific to your organization that may force the decision to have two different deployments of utility network. I didn't see any from the brief description posted. 

[RobertKrisher]

Looking at the Water Utility Network Foundation it sounds like this is all a single utility network, with a single water domain. Each separate area of your network would belong to a single water system subnetwork. The drinking water and agricultural water would both belong to the same system subnetwork, since you said that the same water provided to the drinking subnetwork would flow into the agricultural subnetwork.

You can differentiate the drinking water features from the agricultural features by using the WaterType field on the pipes, as well as by creating different subnetworks for them. If track the content of the agricultural water using one or more meters for an area, then you can create a DMA subnetwork for the agricultural water that originates at each meter. The backflow preventers will limit the agricultural water subnetworks to those areas.